Hi friend, sorry for my bad linguage! Easiest and cheapest way to document power increase is shooting on a book with thin pages before and after intervention e.g. old telephone book or old song book of church. I saw a youtube video for a couple of years about modification the brass cylinder of a crosman CO2 pistol. The main things were: 1. Reduce the diameter of the pin going thru the cylinder ONLY IN THE MIDDLE NOT AT THE BEGINNING AND END- this intervention alone let you win power!!!!!! 2. Cutting/reducing the "gewinde" 3. Modificate the ports by drilling it in a 45 degree angle to increas the flow of the gas 4. Absolutely necessary!!!!!!! Change the spring by using a stronger one. Best wishes mick
I made mods to a similar gun, the crosman 2240. Cut the threads, bored the cylinder out to the max, opened up the ports and spring mods. My shot count went down to about 1/3 of what it used to be and it power went up much much harder hits. I cant remember the exact fps but it was stock at about 450 and ended up well over 600 fps. Don't hold back on any part of the modding, that is what makes it worth doing. As for the flow and the pressure mentioned in this video, it is all wrong. the more you open it up the better. the pressure point is at the pellet in the barrel. The more you open it up, the more the flow into the barrel where it makes all the difference. There is no sweet spot of flow and pressure. More flow into the barrel builds up more pressure accelerating the pellet all the way till it exits the barrel at max velocity.
The Crosman 2240 is a 22 pistol. Running some numbers a typical 22 weighs 0.927g (sorry, I find grains meaningless) and 600fps would produce 15.5J = 11.43 ft lb The sweet spot for a competition target pistol, which are all 177, is just under 500fps. If going faster was more accurate they would tune for faster. There is a sweet spot. The volume of a 22 barrel is greater than a 177, so it needs more gas released into it. The speed of release, the gas flow rate, is important. This is the venturi between valve and barrel. The transfer port and valve hole may be opened, but not the hole in the barrel. The hole in the barrel may be arrised to smooth the lip and remove any burr, but with greatest care - by hand with a fine diamond jewellers tool. Tuning a venturi is a black art. Ideally it wants a slight convex profile through it, with rounded shoulders, to improve gas flow rate. It's more witchcraft than science though, there's a lot of stuff going on, that is is CO2 not air, it goes around corners, the pressure and velocity, rate of change, - there's only so much we can do - like use a tapered reamer from both ends (my old dad would have been able to make a curved hole by making the reamer wobble off axis, master toolmaker). I surmise we need two things here - the right quantity of gas and the right gas flow rate. It's no good still releasing the gas after the pellet has left the muzzle. There is a sweet spot. The best if not only way to find it is by grouping tests. I know they call the 2240 the Ratcatcher but a pistol is a very poor hunting weapon, it takes too long to bring to bear. First you must hit the vermin, and they disoblige by moving. I get a hair over 2 ft lb from my 85yo Webley Junior, it can and has many many times killed a rat point bank, execution not hunting. The rat trap. My CP2 pistol produces some 4.6 ft lb, that too will easily execute a rat. A pistol is for shooting targets and killing tin cans.
After cutting off the threads of the valve cap and grinding the inside of the cap for more capacity. Compare the threads you now have, by how far it screws in.The remaining threads you now have not used and exposed in the valve body, can now be ground off to give more volume, but not too far up to damage the threads needed for the cap.
I love these guns. I have modded my first .22 and have hit nearly 700fps. I recently got another and installed an extremely weak valve spring and stretched the hammer spring. This only added an average of 10fps. It appears the valve volume and port size increase make the most improvement.
I broke my Chronograph so I can't remember the velocity but I do remember I got the Muzzle Energy to almost 11 foot pounds with a Crosman hollow point so that's not bad for a CO2,... I have a PCP, a Gas Ram rifle, Springer &Multi Pump but the Chaser is my most used around my property
Great video, thanks so much. Increasing the gas flow will increase pellet velocity until the pressure in a standard C02 cartridge becomes the limiting factor. I'm sure manufacturers de-tune just a little in order to keep shot count at a decent level, but not much. So there may be very small gains available. When velocity is on the edge of being insufficient, even a small gain can help a lot!
@@davidyummus6259 It's a good tradeoff for you and me, but some may complain about low shot count. I have the .177, and thinking about getting a weaker spring. Like you, I think a stronger hammer spring is not the way to go. The trigger pull is too nice to compromise.
@@Bob_Adkins My chrono is now dead but at the time it was closer to 23% so with a common Crosman 14.3 hollow point, the muzzle energy came in at like 10.7
Can’t wait to see the outcome when you make it work.....I have the same pistol.22 ..with a aluminum silencer I had made..and a red dot sight..I use a 9 gr... pellet for plinking..very fast ..and a 16 gr. For better damage.....but yeah definitely needs more power.....keep up the good work...nice video....👍
The drill bit I used to drill out the cylinder was 27/64 (10.5mm) & I drilled it 5mm deep (approx 3/16) & replaced that spring. I did drill out the ports on the .22 but I kinda wish I didn't lol,... Did the same cylinder mods to the .177 but did NOT do the ports & I think I like it :) Still don't have a Chronograh, work has been tight with the dreaded virus but I hope to have one soon to do some pellet speed tests. My shot count is down so I think & really do have more air behind the pellet.
Thanks for the insight. It motivated me to give it a try. I’ll just change the spring first. If it crono indicates an increase from ~ 550 FPS aver. To ~ 600+ aver. I will call it good! This gun is a tack driver @ 535 to 560 FPS and for its intended purpose 600+ FPS would put frosting on the cake..
Take the burrs out of the action tube where the hammer rides and rebuild the whole thing properly and the 177 pistol can deliver over 500fps in stock form, which is more than it says on the box. The box says the long carbine 177 barrel can deliver 600fps, I have not run it through chrono but believe it will go over that without modifying any parts. I use the CP2 as a target pistol and find that 480-490fps is ideal where it is most efficient and delivers a very small spread of fps over some 55 shots. For the 177 4.5mm the maximum transfer port is 3.5mm or the pellet can get stuck in the port.
A quick down and dirty from my 177 set up as pistol but with the long barrel - various pellets average 570fps. This is with stock springs, no spacers, stock valve, but all nicely slicked up and gas tight, slightly enlarged transfer port. Highest energy 7 ft lb. I do intend to build up a long barrel, parts are on order. However I intend to optimise for the long barrel i.e. for grouping not power, and expect to achieve a little over 600fps and up to 8 ft lb I have already discovered that pushing the pellet too fast the grouping deteriorates. A lump hammer is for breaking bricks not driving tacks. First you have to hit it.
Since last I have acquired a second CP2 and set up as long rifle. It appears to have been assembled better than the first, less work needed to fettle it. Essentially out of the box the first 177 shots were over 600fps, about 630 fps and the CO2 self-regulating to +/-3.5 fps, which is very good and near enough match standard. And around 5 mags at that on a colder day, and two more when it is warmer. The point is the velocity does not change much with temperature when it self-regulates, only the number of shots. With a little more work and practice I've got it to punch 6mm grouping holes in a card target, and I am not a good shot. About 7.5 ft lb, which is about as much as I think we should ask of this little airgun long rifle, which essentially has a target pistol mechanism, if we want accuracy for short to mid range. Do not ask it for too much power because the accuracy suffers badly, the spread goes to pot, and the shot count is disastrous. On its first capsule, after zeroing the scope, I spotted a rat, stood, shouldered and potted it at 20 metres. Power is adequate.
An easy modification to increase power would be to insert a small shim into the hammer to precompress the spring. Initially, my pistol had a disappointing performance of 300fps ( 20 joules). With a 1cm wedge, the power is around 450fps (9 joules).
I'm not sure what you mean by wedge,... I think I understand what you mean because when my gun is NOT cocked & the hammer spring is NOT compressed, I hear the hammer move around freely so there is a little room for a shim to take up that slack but if pressure was put on the spring by stretching the spring or adding too many shims then wouldn't the hammer open the valve ?
@@davidyummus6259 Google traduction problem. I mean "shim", a piece of cylindrical metal that I put inside the hammer in front of the spring. Yes, must carefully choose the length of the shim. The hammer spring must not be too compressed, otherwise, it will press open the valve. It's a kind of equilbrium between the strenght of the valve spring and the hammer spring.
@@christianlau2870 Okay, that is what I thought,... I have replaced the valve return spring for a lighter one so I have already reduced the resistance of the valve opening so I will have to go easy on the shim ;)
@@dinofabrizzi2116 and you ? Do you know how to calculate the energy of the pellet ? E=1/2*m*v^2 with v in m/s and m in kg, ... and E in joules. 1 fps = 0.0254*12 m/s
dindnt drilling the cylinder just make the preetention on the valvespring mutch lower, so your valvespring is now even weaker? an now the cylinder is conical in shape after the drillbit, and the sping can potetialy get missaligned in the new drilled space, and thats is why people cut the threads too get more space for gas
If the chamber valve is what stops the CO2 from completely letting all it's air out at one time then how long it stays open and not the chamber size is what matters. At some point you would be working off the exact pressure of the CO2 itself. Then if that's the case the size of the pierce valve comes into play. Or am I missing something here.
The size of the Pierce Valve/Hole I think would determine "Recovery" time of how long it takes to re pressurize/fill the chamber after a shot but I like that you are thinking,... I think you are correct that the most important is how long the Poppet Valve is open to release pressurized air & then I think Port size to let a large VOLUME of air out at HIGH pressure & yes I think if you went too large on Port size then you could actually LOSE Pressure & this is what happened (I think) on my .177 version. I'm thinking of a Garden hose with adjustable nozzle to describe my thoughts on Port size,... You need VOLUME of water AND Pressure with a garden hose nozzle adjustment so there is a sweet spot,... I chose to lower the tension on the Poppet Valve return spring instead of a stronger Hammer spring to allow the Poppet Valve to open easier, therefore earlier & maybe stay open longer from less resistance to close it. I absolutely gained more power from more air flow because I only get 20 shots before I drop power instead of 30 to 35 with the factory rifle but I honestly don't know which Mod made the difference, I should have done one at a time but I think the lighter return spring leaving the valve open longer may have been the trick,... The only reason I made more room in the chamber was to ensure that a LOT of air was available when the valve opens, any excess just stays in the chamber so nothing lost I think. Did I gain or lose by opening the chamber ?... I have no idea but if I bought a new Rifle then I would certainly start with the valve return spring to open the valve more before doing anything else.
@@davidyummus6259 I believe your absolutely right. Your one of the only ones who decided that a stronger mainspring will be harder on the gun and a lighter valve spring will be just as good. Is there something that stops the poppet valves travel? With a lighter spring there the main spring and hammer should send it farther back? Can that be modified so it will take advantage of your larger chamber? I just got an air bug so this now interested me I want to get a decent increase and keep maybe 30 shot count. You have good common sense.
@@joe-dp3ng I made the same mods to my .177 version but it's not as good, maybe even lost power due to me drilling the .177 Ports the same oversize as the .22,... The Poppet Valve on the .177 sometimes stays open & dumps all the air from the Cartridge so the light spring I chose at the hardware Store is probably right on the edge of being to light.
@@joe-dp3ng looking back, I wish I added the lighter spring to open the vale longer without doing any other mods but I did not have a Chronograph for testing.
@@davidyummus6259 ok got it. But can you tell me the one best thing to do so I can gain some but not to much? I want to learn from what you did. I have always known it's best to get info. Thanks in advance.
Also I have a adapter I got on eBay from a guy who makes them to covert the pistol to HPA works good...fits in co2 chamber and screws closed just like the chamber cap..but it has a fitting for a remote line connection........👍
@@TheCellCreator the nominal 850psi is towards the upper end and some 5860kPa (~60kg/cm2 which is an oddball unit). There will be pressure from the spring but it is insignificant compared to that. I can compress the spring flat between finger and thumb. I weigh about 100kg and 60kg is about 130-lb. Anything less than 5% is generally considered insignificant. As with a car engine, the valve springs are there to return the valves not keep them shut, the gas pressure inside does that. The springs cannot be so strong that the cams cannot lift them. The surface area of the valve is that of a frustum of a cone. I have not calculated that but is is far less than 1 cm^2. The hammer delivers a considerable blow to open it briefly against the gas pressure. I use "back of envelope" calculations because it doesn't really matter what the numbers are to understand how it works, ballpark is good enough. And we are limited as to what we can do to the system. Have fun.
@@TheCellCreator I have a "service box" of springs to try out. What increase in fps are you getting by using a lighter spring? 3kg is 5% of 60kg so it is "not significant" in engineering terms (back of envelope) i.e. variation in vapour pressure may be greater. But note the surface area of the valve is considerably less than 1cm^2 - so the gas is applying less than 60kg and then plus the 3kg. The valve spring must not produce significant pressure (must is not the same as does not) - The principle for self-regulation is to get the impact of the hammer to balance the gas pressure so that the same quantity of gas (PVT and all that) is released each time whatever the vapour pressure. The same principle is used on an industrial gas bottle regulator, spring and diaphragm. For that our valve spring must not produce significant pressure, it must rely on vapour pressure - and still work reliably (nb more Timex than Swiss Watch). Bear in mind that I am deliberately tuning the pistol to produce just under 500fps for best grouping accuracy. I have already found that pushing the pistol to 520-540fps /reduces/ its accuracy. Shooting target at 10 metres there is little drop from the 177 until below 420fps i.e. dead capsule. 460-490fps will go clean though a tin can. In summer I was getting over 65 good shots with less than +/-4fps (480-490-ish), with like another 20 shots for plinking as the capsule died. Adjusting the hammer spring, as is possible with some Crosman, can dial in the sweet spot, but imo tuning the regulation will be at the valve assembly. My experiments with a lens dew heater indicate that the entire breech and barrel has to be kept at stable temperature, not just the capsule and valve. Probably thermal mass and conductivity, gas laws. Not a practical solution. Lagging the lot might work but the dew heater is awkward. Long time since I've wound heater tubes ;) Besides which when it is too cold for the CO2, it is too cold for me to play in the garden ;)
@@TheCellCreator there's some witchcraft too. The weaker spring will open for longer duration, which releases a greater quantity of gas. However the Crosman 2300S puts a sleeve inside the valve chamber to reduce its volume to improve accuracy. The logic here may be to use less gas, to have a higher pressure in the valve chamber for longer for more shots per capsule, for greater consistency (spread), less fps spread, better grouping. I'm getting +/-4fps spread (overall spread, not standard deviation) which is as good as some competition PCP target pistols. Some of the stuff is counter-intuitive, and I'm after accuracy over power.
@@TheCellCreator It was a wish list but then read of reliability problems. I now reckon the CP2 can offer better accuracy. It has an expensive rear sight I would have to discard for a red dot, my eyesight. And I would need a silencer on it, thus discarding the fancy front sight. I do like the adjustment knob on it which I think can be done to the CP1 but not the CP2 due to the way the back end is fastened (there may be a way around that). There is stuff to be learnt from the 2300T.
@@TheCellCreator glad to hear no problems. Problems are usually exaggerated and where they've done something stupid. Silencer? I have presbyopia (age) cannot focus on iron sights and target. But not astigmatic. Hence the red dot I am not a good shot, but that's why I shoot pistol, not because it is easy. Either hand or both. Arthritis, right shoulder is strongest, left is most stable. Right eye. Legs can pack up and need to shoot seated. Resting on a bag is not as much fun, may as well clamp it in a vise. From what I have seen of the 2300S on YT, the CP2 is easily as accurate.
It sucks that you do all that without even having a 30$ chinese chronograph but i like much more your ideas than all the others options i've seen so far. I think i'll make a complete engineering analysis of the gun/riffle and calculate in theory what is the best output we could get from it in different levels of modifications, simple parts swap, easy modifications, modifications that need more skills and complete ultimate modifications with eventually making new parts. I'm pissed off seeing people trying a bunch of random things, drilling to much, using wrong spring, using a harder spring but also keeping a hard spring on the other side etc... i think we can calculate all of those datas and get close to the best we can milk out of that gun/riffle people try a bunch of random shit but it can all be calculated, it's just a numbers game and i see no one exposing their extended calculations.
Exactly! Amateurs almost everywhere without cheap ass chrono. They even can’t say even an estimate of what they achieved. I bet doing all the modifications would break performance significantly. Uneven shots and 1/3 of them. Even drilling port I think breaks self regulation and stability. Only increasing chamber volume little bit would be reasonable approach. How much is the question because further down the line we get loss of accuracy at some point. All I want to achieve is to stay under legal limits and also not have 1/3 of shots from one co2. Probably there were some reasons to not to give full legal power. Number of shots or uneven power, faster wear of seals , trigger etc. I don’t know. At least I think if chamber was drilled too much it’s easy to go back by placing some 3D printed tube filling that space to previous volume. I’ll get chrono soon.
Hi my name is gene I have a chaser in 22 just took it apart and cut half the threads drilled it like u did and opened up the brass port can’t really tell if it made a difference but I’ll know for sure next week waiting on a crono I live in frederick md let me know if I didn’t do something right thank u gene
David, this would have been a fantastic effort if you had chrony'd before and after. I am very intrigued about ways to increase power in a CO2 powered Diana Chaser and you've presented a couple of excellent ideas, with good detail on how to do them. Please let us know what fps you get when you get your chrony.
David kind of off topic. All of my air guns are multi pump pneumatics never had a co2 model. Think you could do a video of the pros and cons of each? Wondering about power, noise and whatever.
No I don't but it's simple,... Tight but simple. 3 set screws hold it in place to the breech but they are small & easy to lose so remove them on a towel or blanket or something,... 2 o'rings, one either side of the port, be careful that you don't twist the barrel, rock it gently back & forth as you pull it out so you don't damage those o'rings & use a drop of oil on them when re installing the barrel,... If you need to replace them, they are a Metric, 1mm cross section, 9mm outside diameter & 7mm inside diameter. There is also an o'ring on the inside of the end of the barrel which is used to seal the bold when closed.
It did but not really a lot but again, I didn't & still don't have a chronograph to know for sure,... Making more room in the cylinder for more air made a good difference.
Hi David , thanks for your video. You made very clear explaination. 👍 But I have one question ...... did you compressed the new spring to the length of the old spring ? Or could I simply cut off a portion the new spring to match the length of the old one ? Is it going to work ? Thanks !
Yoy don't have a dorr betwin co2 and valve. So you increased the valve chamber for nothing. The co2 and the valve is a comon body.let imaging If it was a dorr betwin co2 and the valve chember. After every shoot you take, after 1 second the dorr open and the chamber is full again with co2. In that case is ok to increase the valve chamber but is not the case. So you are shoting strait from the co2 and the result is if you was having a smaler or a biger valve chamber it was the same power as the original valve. Sorry for my english. I hope you understand what i want to say
Not exactly because Co2 goes through tiny hole in puncturing pin. It doesn’t have time to refill valve chamber in that small time window. The same goes further with port. What is the point of drilling bigger hole in port when valve is smaller anyway. The smallest diameter limits the flow of gas anyway , in that case the valve is the limiter. In my opinion increasing chamber volume and modifying the springs will give the most gain but I would firstly start with springs and chronograph. Then I would calculate how much volume I get by modifying the chamber, probably not too much and I wouldn’t do it because it’s permanent. Springs alone give more time to escape co2 more efficiently. Increasing chamber will lower the number of shots which is also not good
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Hi friend, sorry for my bad linguage!
Easiest and cheapest way to document power increase is shooting on a book with thin pages before and after intervention e.g. old telephone book or old song book of church.
I saw a youtube video for a couple of years about modification the brass cylinder of a crosman CO2 pistol.
The main things were:
1. Reduce the diameter of the pin going thru the cylinder ONLY IN THE MIDDLE NOT AT THE BEGINNING AND END- this intervention alone let you win power!!!!!!
2. Cutting/reducing the "gewinde"
3. Modificate the ports by drilling it in a 45 degree angle to increas the flow of the gas
4. Absolutely necessary!!!!!!! Change the spring by using a stronger one.
Best wishes mick
I made mods to a similar gun, the crosman 2240. Cut the threads, bored the cylinder out to the max, opened up the ports and spring mods. My shot count went down to about 1/3 of what it used to be and it power went up much much harder hits. I cant remember the exact fps but it was stock at about 450 and ended up well over 600 fps. Don't hold back on any part of the modding, that is what makes it worth doing. As for the flow and the pressure mentioned in this video, it is all wrong. the more you open it up the better. the pressure point is at the pellet in the barrel. The more you open it up, the more the flow into the barrel where it makes all the difference. There is no sweet spot of flow and pressure. More flow into the barrel builds up more pressure accelerating the pellet all the way till it exits the barrel at max velocity.
The Crosman 2240 is a 22 pistol. Running some numbers a typical 22 weighs 0.927g (sorry, I find grains meaningless) and 600fps would produce 15.5J = 11.43 ft lb
The sweet spot for a competition target pistol, which are all 177, is just under 500fps. If going faster was more accurate they would tune for faster. There is a sweet spot.
The volume of a 22 barrel is greater than a 177, so it needs more gas released into it.
The speed of release, the gas flow rate, is important. This is the venturi between valve and barrel. The transfer port and valve hole may be opened, but not the hole in the barrel. The hole in the barrel may be arrised to smooth the lip and remove any burr, but with greatest care - by hand with a fine diamond jewellers tool.
Tuning a venturi is a black art. Ideally it wants a slight convex profile through it, with rounded shoulders, to improve gas flow rate. It's more witchcraft than science though, there's a lot of stuff going on, that is is CO2 not air, it goes around corners, the pressure and velocity, rate of change, - there's only so much we can do - like use a tapered reamer from both ends (my old dad would have been able to make a curved hole by making the reamer wobble off axis, master toolmaker).
I surmise we need two things here - the right quantity of gas and the right gas flow rate. It's no good still releasing the gas after the pellet has left the muzzle.
There is a sweet spot. The best if not only way to find it is by grouping tests.
I know they call the 2240 the Ratcatcher but a pistol is a very poor hunting weapon, it takes too long to bring to bear. First you must hit the vermin, and they disoblige by moving.
I get a hair over 2 ft lb from my 85yo Webley Junior, it can and has many many times killed a rat point bank, execution not hunting. The rat trap. My CP2 pistol produces some 4.6 ft lb, that too will easily execute a rat. A pistol is for shooting targets and killing tin cans.
After cutting off the threads of the valve cap and grinding the inside of the cap for more capacity. Compare the threads you now have, by how far it screws in.The remaining threads you now have not used and exposed in the valve body, can now be ground off to give more volume, but not too far up to damage the threads needed for the cap.
I love these guns. I have modded my first .22 and have hit nearly 700fps. I recently got another and installed an extremely weak valve spring and stretched the hammer spring. This only added an average of 10fps. It appears the valve volume and port size increase make the most improvement.
I broke my Chronograph so I can't remember the velocity but I do remember I got the Muzzle Energy to almost 11 foot pounds with a Crosman hollow point so that's not bad for a CO2,... I have a PCP, a Gas Ram rifle, Springer &Multi Pump but the Chaser is my most used around my property
Great video, thanks so much. Increasing the gas flow will increase pellet velocity until the pressure in a standard C02 cartridge becomes the limiting factor. I'm sure manufacturers de-tune just a little in order to keep shot count at a decent level, but not much. So there may be very small gains available. When velocity is on the edge of being insufficient, even a small gain can help a lot!
Yeah, I gained a little more than 20% muzzle energy but my shot count is down to 20 shots but I am happy with it.
@@davidyummus6259 It's a good tradeoff for you and me, but some may complain about low shot count. I have the .177, and thinking about getting a weaker spring. Like you, I think a stronger hammer spring is not the way to go. The trigger pull is too nice to compromise.
@@davidyummus6259 Forgot to say, 20% more power is not trivial. That would put my .177 from ~625 up to ~750. I would sacrifice 15 shots for that!
@@Bob_Adkins
My chrono is now dead but at the time it was closer to 23% so with a common Crosman 14.3 hollow point, the muzzle energy came in at like 10.7
Can’t wait to see the outcome when you make it work.....I have the same pistol.22 ..with a aluminum silencer I had made..and a red dot sight..I use a 9 gr... pellet for plinking..very fast ..and a 16 gr. For better damage.....but yeah definitely needs more power.....keep up the good work...nice video....👍
The drill bit I used to drill out the cylinder was 27/64 (10.5mm) & I drilled it 5mm deep (approx 3/16) & replaced that spring.
I did drill out the ports on the .22 but I kinda wish I didn't lol,... Did the same cylinder mods to the .177 but did NOT do the ports & I think I like it :)
Still don't have a Chronograh, work has been tight with the dreaded virus but I hope to have one soon to do some pellet speed tests.
My shot count is down so I think & really do have more air behind the pellet.
Thanks for the insight. It motivated me to give it a try. I’ll just change the spring first. If it crono indicates an increase from ~ 550 FPS aver. To ~ 600+ aver. I will call it good! This gun is a tack driver @ 535 to 560 FPS and for its intended purpose 600+ FPS would put frosting on the cake..
Bob did you gain fps,?
Take the burrs out of the action tube where the hammer rides and rebuild the whole thing properly and the 177 pistol can deliver over 500fps in stock form, which is more than it says on the box. The box says the long carbine 177 barrel can deliver 600fps, I have not run it through chrono but believe it will go over that without modifying any parts. I use the CP2 as a target pistol and find that 480-490fps is ideal where it is most efficient and delivers a very small spread of fps over some 55 shots.
For the 177 4.5mm the maximum transfer port is 3.5mm or the pellet can get stuck in the port.
A quick down and dirty from my 177 set up as pistol but with the long barrel - various pellets average 570fps.
This is with stock springs, no spacers, stock valve, but all nicely slicked up and gas tight, slightly enlarged transfer port. Highest energy 7 ft lb.
I do intend to build up a long barrel, parts are on order. However I intend to optimise for the long barrel i.e. for grouping not power, and expect to achieve a little over 600fps and up to 8 ft lb
I have already discovered that pushing the pellet too fast the grouping deteriorates. A lump hammer is for breaking bricks not driving tacks. First you have to hit it.
Since last I have acquired a second CP2 and set up as long rifle. It appears to have been assembled better than the first, less work needed to fettle it. Essentially out of the box the first 177 shots were over 600fps, about 630 fps and the CO2 self-regulating to +/-3.5 fps, which is very good and near enough match standard.
And around 5 mags at that on a colder day, and two more when it is warmer. The point is the velocity does not change much with temperature when it self-regulates, only the number of shots.
With a little more work and practice I've got it to punch 6mm grouping holes in a card target, and I am not a good shot.
About 7.5 ft lb, which is about as much as I think we should ask of this little airgun long rifle, which essentially has a target pistol mechanism, if we want accuracy for short to mid range.
Do not ask it for too much power because the accuracy suffers badly, the spread goes to pot, and the shot count is disastrous.
On its first capsule, after zeroing the scope, I spotted a rat, stood, shouldered and potted it at 20 metres. Power is adequate.
An easy modification to increase power would be to insert a small shim into the hammer to precompress the spring. Initially, my pistol had a disappointing performance of 300fps ( 20 joules). With a 1cm wedge, the power is around 450fps (9 joules).
I'm not sure what you mean by wedge,... I think I understand what you mean because when my gun is NOT cocked & the hammer spring is NOT compressed, I hear the hammer move around freely so there is a little room for a shim to take up that slack but if pressure was put on the spring by stretching the spring or adding too many shims then wouldn't the hammer open the valve ?
@@davidyummus6259 Google traduction problem. I mean "shim", a piece of cylindrical metal that I put inside the hammer in front of the spring. Yes, must carefully choose the length of the shim. The hammer spring must not be too compressed, otherwise, it will press open the valve. It's a kind of equilbrium between the strenght of the valve spring and the hammer spring.
@@christianlau2870
Okay, that is what I thought,... I have replaced the valve return spring for a lighter one so I have already reduced the resistance of the valve opening so I will have to go easy on the shim ;)
You have no idea what joules are about !😆😆😆😂😂😅😅😅😅..
@@dinofabrizzi2116 and you ? Do you know how to calculate the energy of the pellet ?
E=1/2*m*v^2
with v in m/s and m in kg, ... and E in joules.
1 fps = 0.0254*12 m/s
dindnt drilling the cylinder just make the preetention on the valvespring mutch lower, so your valvespring is now even weaker?
an now the cylinder is conical in shape after the drillbit, and the sping can potetialy get missaligned in the new drilled space, and thats is why people cut the threads too get more space for gas
If the chamber valve is what stops the CO2 from completely letting all it's air out at one time then how long it stays open and not the chamber size is what matters. At some point you would be working off the exact pressure of the CO2 itself. Then if that's the case the size of the pierce valve comes into play. Or am I missing something here.
The size of the Pierce Valve/Hole I think would determine "Recovery" time of how long it takes to re pressurize/fill the chamber after a shot but I like that you are thinking,... I think you are correct that the most important is how long the Poppet Valve is open to release pressurized air & then I think Port size to let a large VOLUME of air out at HIGH pressure & yes I think if you went too large on Port size then you could actually LOSE Pressure & this is what happened (I think) on my .177 version.
I'm thinking of a Garden hose with adjustable nozzle to describe my thoughts on Port size,... You need VOLUME of water AND Pressure with a garden hose nozzle adjustment so there is a sweet spot,... I chose to lower the tension on the Poppet Valve return spring instead of a stronger Hammer spring to allow the Poppet Valve to open easier, therefore earlier & maybe stay open longer from less resistance to close it.
I absolutely gained more power from more air flow because I only get 20 shots before I drop power instead of 30 to 35 with the factory rifle but I honestly don't know which Mod made the difference, I should have done one at a time but I think the lighter return spring leaving the valve open longer may have been the trick,... The only reason I made more room in the chamber was to ensure that a LOT of air was available when the valve opens, any excess just stays in the chamber so nothing lost I think.
Did I gain or lose by opening the chamber ?... I have no idea but if I bought a new Rifle then I would certainly start with the valve return spring to open the valve more before doing anything else.
@@davidyummus6259 I believe your absolutely right. Your one of the only ones who decided that a stronger mainspring will be harder on the gun and a lighter valve spring will be just as good. Is there something that stops the poppet valves travel? With a lighter spring there the main spring and hammer should send it farther back? Can that be modified so it will take advantage of your larger chamber? I just got an air bug so this now interested me I want to get a decent increase and keep maybe 30 shot count. You have good common sense.
@@joe-dp3ng
I made the same mods to my .177 version but it's not as good, maybe even lost power due to me drilling the .177 Ports the same oversize as the .22,... The Poppet Valve on the .177 sometimes stays open & dumps all the air from the Cartridge so the light spring I chose at the hardware Store is probably right on the edge of being to light.
@@joe-dp3ng
looking back, I wish I added the lighter spring to open the vale longer without doing any other mods but I did not have a Chronograph for testing.
@@davidyummus6259 ok got it. But can you tell me the one best thing to do so I can gain some but not to much? I want to learn from what you did. I have always known it's best to get info. Thanks in advance.
It also be decreasing your standard deviation by probably not letting the CO2 be as cold for the repeat shot
Also I have a adapter I got on eBay from a guy who makes them to covert the pistol to HPA works good...fits in co2 chamber and screws closed just like the chamber cap..but it has a fitting for a remote line connection........👍
proyectoniebla ...you can get adapter at......Sales@AlliancsHobby.com...hope this helps....👍
The valve spring does not keep the valve closed, the gas pressure does, it's about 850psi. It doesn't matter how strong or weak the valve spring is.
@@TheCellCreator the nominal 850psi is towards the upper end and some 5860kPa (~60kg/cm2 which is an oddball unit). There will be pressure from the spring but it is insignificant compared to that. I can compress the spring flat between finger and thumb. I weigh about 100kg and 60kg is about 130-lb. Anything less than 5% is generally considered insignificant.
As with a car engine, the valve springs are there to return the valves not keep them shut, the gas pressure inside does that. The springs cannot be so strong that the cams cannot lift them.
The surface area of the valve is that of a frustum of a cone. I have not calculated that but is is far less than 1 cm^2. The hammer delivers a considerable blow to open it briefly against the gas pressure.
I use "back of envelope" calculations because it doesn't really matter what the numbers are to understand how it works, ballpark is good enough. And we are limited as to what we can do to the system.
Have fun.
@@TheCellCreator I have a "service box" of springs to try out.
What increase in fps are you getting by using a lighter spring?
3kg is 5% of 60kg so it is "not significant" in engineering terms (back of envelope) i.e. variation in vapour pressure may be greater. But note the surface area of the valve is considerably less than 1cm^2 - so the gas is applying less than 60kg and then plus the 3kg.
The valve spring must not produce significant pressure (must is not the same as does not) -
The principle for self-regulation is to get the impact of the hammer to balance the gas pressure so that the same quantity of gas (PVT and all that) is released each time whatever the vapour pressure. The same principle is used on an industrial gas bottle regulator, spring and diaphragm. For that our valve spring must not produce significant pressure, it must rely on vapour pressure - and still work reliably (nb more Timex than Swiss Watch).
Bear in mind that I am deliberately tuning the pistol to produce just under 500fps for best grouping accuracy. I have already found that pushing the pistol to 520-540fps /reduces/ its accuracy. Shooting target at 10 metres there is little drop from the 177 until below 420fps i.e. dead capsule. 460-490fps will go clean though a tin can. In summer I was getting over 65 good shots with less than +/-4fps (480-490-ish), with like another 20 shots for plinking as the capsule died.
Adjusting the hammer spring, as is possible with some Crosman, can dial in the sweet spot, but imo tuning the regulation will be at the valve assembly.
My experiments with a lens dew heater indicate that the entire breech and barrel has to be kept at stable temperature, not just the capsule and valve. Probably thermal mass and conductivity, gas laws. Not a practical solution. Lagging the lot might work but the dew heater is awkward. Long time since I've wound heater tubes ;)
Besides which when it is too cold for the CO2, it is too cold for me to play in the garden ;)
@@TheCellCreator there's some witchcraft too. The weaker spring will open for longer duration, which releases a greater quantity of gas. However the Crosman 2300S puts a sleeve inside the valve chamber to reduce its volume to improve accuracy. The logic here may be to use less gas, to have a higher pressure in the valve chamber for longer for more shots per capsule, for greater consistency (spread), less fps spread, better grouping. I'm getting +/-4fps spread (overall spread, not standard deviation) which is as good as some competition PCP target pistols.
Some of the stuff is counter-intuitive, and I'm after accuracy over power.
@@TheCellCreator It was a wish list but then read of reliability problems. I now reckon the CP2 can offer better accuracy. It has an expensive rear sight I would have to discard for a red dot, my eyesight. And I would need a silencer on it, thus discarding the fancy front sight.
I do like the adjustment knob on it which I think can be done to the CP1 but not the CP2 due to the way the back end is fastened (there may be a way around that).
There is stuff to be learnt from the 2300T.
@@TheCellCreator glad to hear no problems. Problems are usually exaggerated and where they've done something stupid.
Silencer?
I have presbyopia (age) cannot focus on iron sights and target. But not astigmatic. Hence the red dot
I am not a good shot, but that's why I shoot pistol, not because it is easy. Either hand or both. Arthritis, right shoulder is strongest, left is most stable. Right eye. Legs can pack up and need to shoot seated. Resting on a bag is not as much fun, may as well clamp it in a vise.
From what I have seen of the 2300S on YT, the CP2 is easily as accurate.
Great video! Thanks for sharing.
It sucks that you do all that without even having a 30$ chinese chronograph but i like much more your ideas than all the others options i've seen so far.
I think i'll make a complete engineering analysis of the gun/riffle and calculate in theory what is the best output we could get from it in different levels of modifications, simple parts swap, easy modifications, modifications that need more skills and complete ultimate modifications with eventually making new parts.
I'm pissed off seeing people trying a bunch of random things, drilling to much, using wrong spring, using a harder spring but also keeping a hard spring on the other side etc... i think we can calculate all of those datas and get close to the best we can milk out of that gun/riffle people try a bunch of random shit but it can all be calculated, it's just a numbers game and i see no one exposing their extended calculations.
Exactly! Amateurs almost everywhere without cheap ass chrono. They even can’t say even an estimate of what they achieved. I bet doing all the modifications would break performance significantly. Uneven shots and 1/3 of them. Even drilling port I think breaks self regulation and stability. Only increasing chamber volume little bit would be reasonable approach. How much is the question because further down the line we get loss of accuracy at some point. All I want to achieve is to stay under legal limits and also not have 1/3 of shots from one co2. Probably there were some reasons to not to give full legal power. Number of shots or uneven power, faster wear of seals , trigger etc. I don’t know. At least I think if chamber was drilled too much it’s easy to go back by placing some 3D printed tube filling that space to previous volume. I’ll get chrono soon.
That with the spring Was a good idea . Then the export Port for 8 Euro. But i will wait untill i am in Austria. Here in Germany it is not liegel .
So did you get your chrony yet I'm excited to see the difference thanks
I like your thought true volume an pressure is a fine line going to try this if I gain 50fps it's a plus
You can order a valve and if I remember correctly they are $10 bucks. Problem is it takes months to get.
Amigo aonde encontro essa válvula disparadoura pra comprar aqui no Brasil não acha
Hi my name is gene I have a chaser in 22 just took it apart and cut half the threads drilled it like u did and opened up the brass port can’t really tell if it made a difference but I’ll know for sure next week waiting on a crono I live in frederick md let me know if I didn’t do something right thank u gene
Did it ever work out? Or did you just give up on the idea to put more power to the chaser?
On my one I have made a valve and it has a Farley large hole so it puts more air through
What is the length and diameter of the spring?
Here we can buy a export Port for 8 Euro to get more Joule. So it makes a diference .
Isn't 4 cubics giving more pressure , v/5 cubics ,filled with only 4 cubics of air
show us result of your modification of the fps reading before mod and fps reading after mod so we can see how much power really it increase
David, this would have been a fantastic effort if you had chrony'd before and after. I am very intrigued about ways to increase power in a CO2 powered Diana Chaser and you've presented a couple of excellent ideas, with good detail on how to do them. Please let us know what fps you get when you get your chrony.
Will do.
David kind of off topic. All of my air guns are multi pump pneumatics never had a co2 model. Think you could do a video of the pros and cons of each? Wondering about power, noise and whatever.
Yeah :)
Let me think about putting that together ;)
Do you have a video on changing the barrel? Ty 👍🏻
No I don't but it's simple,... Tight but simple.
3 set screws hold it in place to the breech but they are small & easy to lose so remove them on a towel or blanket or something,... 2 o'rings, one either side of the port, be careful that you don't twist the barrel, rock it gently back & forth as you pull it out so you don't damage those o'rings & use a drop of oil on them when re installing the barrel,... If you need to replace them, they are a Metric, 1mm cross section, 9mm outside diameter & 7mm inside diameter.
There is also an o'ring on the inside of the end of the barrel which is used to seal the bold when closed.
@@davidyummus6259 thank you David.
so the lighter spring makes a real different? in one of your earlier vids you said it doesent
It did but not really a lot but again, I didn't & still don't have a chronograph to know for sure,... Making more room in the cylinder for more air made a good difference.
Hi David , thanks for your video. You made very clear explaination. 👍
But I have one question ...... did you compressed the new spring to the length of the old spring ? Or could I simply cut off a portion the new spring to match the length of the old one ? Is it going to work ? Thanks !
I didn't bother cutting it as even at full length it was much weaker than the factory one
@@davidyummus6259 Thanks Dave !😄🙏
Amigo aonde arrumo essa válvula disparadoura pra comprar
Oh and I put the same spring in u did
Yoy don't have a dorr betwin co2 and valve. So you increased the valve chamber for nothing. The co2 and the valve is a comon body.let imaging If it was a dorr betwin co2 and the valve chember. After every shoot you take, after 1 second the dorr open and the chamber is full again with co2. In that case is ok to increase the valve chamber but is not the case. So you are shoting strait from the co2 and the result is if you was having a smaler or a biger valve chamber it was the same power as the original valve. Sorry for my english. I hope you understand what i want to say
Seems like a relevant point that warrants an answer
Not exactly because Co2 goes through tiny hole in puncturing pin. It doesn’t have time to refill valve chamber in that small time window. The same goes further with port. What is the point of drilling bigger hole in port when valve is smaller anyway. The smallest diameter limits the flow of gas anyway , in that case the valve is the limiter. In my opinion increasing chamber volume and modifying the springs will give the most gain but I would firstly start with springs and chronograph. Then I would calculate how much volume I get by modifying the chamber, probably not too much and I wouldn’t do it because it’s permanent. Springs alone give more time to escape co2 more efficiently. Increasing chamber will lower the number of shots which is also not good