Bullet Tech Talk GP-11 Secret Revealed
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- เผยแพร่เมื่อ 5 ก.พ. 2025
- Hi Guys: here's a short video about some things in regard to GP-11 ammunition vs commercial or hand loaded .308" dia. bullets that you may finding mildly interesting. Thanks for watching.
Thank you, very educational! This was never explained to us in the Swiss Military sharpshooter training back in the mid eighties. All we knew, it is a dead accurate ammo!😊
The GP11 bullet design is what us cast bullet shooters call a "bore rider". I cast a 180 grain bullet that was specifically designed for the K31. The long undersize nose skims the bore and a shorter driving band at the rear fills the grooves. The GP11 design really was ahead of its time.
Hi Pat: Something I didn't know about cast projectiles. Interesting. And I agree about the design being way ahead of its time. But then again the Swiss "over engineer" just about everything. I think the GP-11 projectiles come from RWS and I wish I could get those for reloading. Thanks for watching and commenting Pat. Have a great day and God Bless.
A fantastic video. Thank you very much for your in depth explanation and great camera work. Much appreciated.
Hi John: Thanks man, very much appreciated. It makes my day (-:
Excellent video. You were telling me how to build a watch instead of the time in the begining of the video but the presentation was flawless. Your summation of the Tactical data you collected was perfect. Thanks for an excellent informative video.
Hi Hamm: Thanks man. I very much appreciate your kind words as well as you taking your time to watch. I hope it can help you in the future.
having reloaded and competed with several k31's, you're spot on, great analysis. From what I understand, Berger is the closest commercial bullet available in the US that even comes close to the profile of the GP11. one of the biggest problems reloaders encounter with this round is seating the bullet out too far and jamming it into the lands resulting in excessive pressure.
great job explaining why this happens
Hi DrMike: Thanks mang. I very much appreciate your feedback.
What about the 175 grain sierra matchkings?
I regularly use the 175 SMKs over RL17- very accurate. Remember to seat them a little deeper and they work great
Extremely well shown ! Never would I have thought that !!
I didn't do all the measuring that you did, but it was obvious the the swiss projectile was seated well within the lands simply by eyeballing the two and measuring the diameter of the projectiles. I first became aware of this when I compared my .308 hand load with the GP11. Big difference. So big, in fact, that I went on an unsuccessful search overseas to find these projectiles. I believe I found them but they would not export them. Great video.
oh yeah, those are pretty tricky projectiles indeed
Cool video Lencac, I've been drooling on gunbroker looking at the eye candy you have on there. Very well done sir. How much money would one have to shell out for a throat erosion tool like that? I have a few Swiss arms including a 43' K31 that was used in many matches proved by all the stickers covering the entire hand guard. My K11 is a beauty, it has a hammerli barrel and looks almost new. Awesome videos man keep up the good work!
The TE gauge I got from Midway and I think it was about $70
This is great, and a relief to me. I took a round of GP11 and stuck the bullet into the end of the muzzle, just to see how far in it would go. Just messing around, wanted to see if the barrel was shot out. To my surprise it went all the way to the brass! I was kinda depressed, thinking the barrel is shot out. But then at the range, at 100 yards, It was grouping great!! Not every time, but that's probably me. I just held the iron sights in the same spot let off 5 rounds, and it was under an inch! And I'm not the best shot. I usually can't pull that off. But it shows me that this old rifle, built in 1939 is more accurate than I can shoot. I'm debating on getting some hunting ammo and taking it out hunting this year or next. Have you ever tried the Norma ammo they have for this? I was just looking, and they had some really high end target ammo, which was pricey. And extremely pricey hunting ammo. Talking 90$ can for 20 rounds. I'm thinking of splurging and buying a few boxes of each. Only one place in Canada sells it, and it goes fast it seems. PPU is alot cheaper, but just would like to see what that norma ammo could do.
Cheers, great vid!
A very informative, and thoughtful video! I might have watched it once when I bought my K31 years back, but have not been able to duplicate GP11 fit and finish in my reloads. This in turn made me watch it again more closely. Hornandy Match bullets and PPU brass never go completely into battery, and need a smart kick to lock completely. I too suspected I had seated the bullet too close to the ogive, but that was not the case for me. I believe you are spot on with the taper of the GP11 bullet, being different, and the PPU brass may be a little thicker on the neck. I have reloaded the brass twice, so I believe the .308 bullet may be pushing the brass against the lands? I may experiment with Sierra bullets which seem to mimic the Swiss taper better.
Hi ybnormal: Thanks! Here's what I would recommend. Take a case that is fully prepped and sized and see if it will chamber in the rifle and go into battery the way it should. And then will the case come out freely. If there is any type of resistance either going in or coming out you may want to tighten up the sizing die setting to bring the shoulder back a little bit. What dies are you using? The Hornady K31 sizing die and a 7.5x55 Swiss sizing die do have slightly different dimension. Make sure the cases are trimmed to the correct length. And then of course be aware of how tight the projectile to lands clearance is. Using my Hornady tool I seat the projectile to 2.250", that's base to ogive. That should give you about .015" clearance at minimum. Depending on throat erosion it may be a little more. K31's are precision rifles. It should not require a second hit on the charging knob. If it does something is not quite right. Let me know how it pans out for you.
I have a RBC press, but am using a Lee Die set. I will take a look at my setting to see if I can resize my case better. I use Hornandy's reloading handbook for my dimensions, but since it is not quite right; I am in your camp now . Sorry for the slow reply, as I did not see yours until I started thinking about my next batch of reloads. @@lencac7952
Very excellent video, thank you very much! I found the same problem. In my opinion the best way is reloding tangent profile bullets.
The FMJ BT. 30 .308. From PPU. Is the closest I’ve found in dimensional terms as it tapers to .306 at its max which is at the rear before the boat tail starts. I would think it would closely follow the Swiss thinking on the Bullet head.
Hey Bodger: Yep, I agree about the PPU 7.5x55 cartridge. However, although the PPU 7.5x55 cartridge is more like the GP11 than any of the commercial .308 bullets available it still lacks the bi-dimensional characteristics of GP11 projectiles. Which I think in total genius. Thanks for watching and taking the time to comment (-:
Superb and easily understood.
thanks mang (-:
Perhaps in addition to lower pressures the nose of the bullet, riding inside the lands, is given directional stability before it's fired. I know the last portion of the barrel at the muzzle is most important to accuracy but perhaps through their testing they found breech end stability has a role as well.
Hi Dave: Good observation and I agree. Being the muzzle crown is the last thing the bullet sees as it exits the barrel if the crown is not absolutely perpendicular to the axis of the bore it will cause the bullet to yaw. But the bullet needs to enter the bore true to the axis of the bore before the crown can do its job properly. Which brings up your point. The two different dia. of the bullet may act as a guide also to get the bullet true in the bore. I would think if the bullet enters the bore cock-eyed it would deform the bullet slightly. So here's a story that got me thinking about that very thing. Years ago I was doing some long range shooting across a canyon with my brother-in-law. It was early in the morning and the sun was at our backs. I was shooting an old Mosin 91/30 that had been shot a bunch back in WWII. And it had a very sloppy muzzle from the way they cleaned those things back then. When I would shoot it I could see the reflection off the back of the hand loaded bullets. And I could see the bullet was cork-screwing through the air. So because it was just an old Mosin we cut off a couple inches of the barrel and recrowned it. Took it back a few days later. Same conditions and no more cork-screwing. But I digress. Plus the GP-11 ammo. is no doubt the finest mil-surplus ammo. there is which doesn't hurt. Question. How much PSI is at the muzzle when the bullet leaves the bore in general on any type of high powered 30 cal. cartridge? I don't know myself so I'd be curious to know what you think. I think 4 to 5 thousand PSI.
@@lencac7952 I couldn't really guess what the pressures might be but it should be that as velocity increases pressure should decrease. It would be interesting too to gauge pressures of the two different bullets at the chamber, to see if your theory about pressures is correct. I find it fascinating how they designed the bullets this way but I've never heard of any other done like that. I thought I had heard somewhere that the cartridge had been modified along with the new K-31 rifle. If so, something like this would maintain usability in the older rifle, but would benefit the newer model in 1931. This is a mystery only the engineering papers would reveal but that was 90 years ago. Seems this is the only way to speculate what they were doing. Have you ever examined the Berger 175 VLD someone else mentioned?
@@blackbirdpie217 I have. The bearing surface is .308" dia. But it does have a really long pointy nose. Keep in mind the K31 is a 7.56mm bore I think so it's not a true .308" bore. So a .308" is a bit of a little tighter fit.
Here, this will save you 20 minutes of your time -- Use tangent ogive bullets when loading 7.5x55 for K31 rifles NOT secant ogive bullets.
I'd like to try some hybrid ogive bullets. But I can't find any.
Hi, I recently tried commercial S&B 7.5 Swiss, they have the same bullet weight as GP 11, the cartridge OAL is just a tat shorter than GP 11, however, the Bullet seems to be a custom 7.5 bullet design, as it basically has an inverted belt (or crimp ring) just in front of the case mouth.
I fired 5 of them from my K31 just afetr 3 GP11 and the poi at 100 meter was spot on.
4 at roughthly an inch spread, I pulled one shot slightly.
Hi Mr79dream: You know I've never tried S&B ammo. through a K31. Nice job. Sounds like the S&B stuff is also worthy. If you were to get crazy and pull a bullet out of one those S&B's and measure with your caliper the diameter on both sides of the channeler, I'd be interested in knowing (-: I've found that the K31 seems to shoot anything I put in it very good to excellent.
@@lencac7952 are you on FB in the Swiss firearms reloading group?
@@lencac7952 They stat the bullet as no 2947 however, that bullet seems not to be in the list of individual components.
If I look at pictures of their other .308 bullets, the "invertes Belt" might just be a crimp ring, which is not actually in the case.
Maybe one of them will fall appart.
@@lencac7952 I have very interesting results
They are using their Bullet 2947 for the 7.5 SWISS which appears to be purpose build 7.5mm
It is tapered like the GP11 but shorter.
S&B
Cartridge OAL 2.987
"
Bullet diameter from tip before crimp groove 0.302"
groove 0.296"
from tip behind groove 0.303"
at the edge of the boat tail 0.308
"
bullet OAL 1.246
"
fine ball powder 46grn
GP11 1984
Cartridge OAL 3.043
Bullet diameter from tip before crimp groove 0.304
groove 0.296
from tip behind groove 0.306
at the edge of the boat tail 0.308
bullet OAL 1.412
rough stick powder 49.5grn
I have only calipers with a dial, no micrometer unfortunately
@@lencac7952 facebook.com/groups/1211094472343312/permalink/2346696038783144/
I would imagine you could shorten the case neck that uses the .308 and neck turn to lower the pressure.
Another permanent solution would be to open the throat to accommodate the
308. Thus allowing the bullet to be seated further out.
Hi Sean: Well, I suppose one could do that. However, I don't see the seating depth being close to the lands being a problem. At least not from my experience. I think it's important to know about this especially for someone new to reloading for K31's. Because of the .306" dia of the GP-11 projectile as opposed to the .308" it does have to normal .100" off the lands which is quite standard for mil-spec standard issue rifles. Thanks for watching and commenting Sean (-:
@@lencac7952 fixing the neck would lower pressure I believe. But I'll admit I know much less than you about these.. 🤔
@@beefcakes27 You are correct about the neck. Turning the neck or even having a bit of a loose fit of the projectile will slightly reduce spike pressure. However, I think the fact that we are pushing a .308" bullet down a barrel that is intended to use .306" bullets is a cause of much greater pressure spike than the neck being turned. Nevertheless, in spite of that the K31's show no signs of over pressure and the K31 action is a very strong action and the velocities are normal. So I don't worry about that.
Outstanding information ! However you talked me out of a K-31 purchase since my future reloaded ammunition would be inadequate compared to the GP-11.
Well, that was a mistake on your part. Prices are skyrocketing on k31's. I've got better accuracy with my handloads than i have with gp11. 168gr sierra matchking over IMR 4895 is a 1/2 moa load at 200 yards.
Hi, can you make a video test of this ammo (gp11) vs ballistic ceramic or steel plate...?
Sir,
I am going to start reloading for my K31 and I was wondering if you ever did or considered using the Speer 175 grain Tipped Match King.
The taper on the TMK is longer than the SMK and seems it might work well. What are your thoughts?
Thank You,
Hi DLKK: First, I think your K31 will shoot very well with anything you put through it. So primarily you need to be able to shoot to the rifles potential. In other words, the K31 is capable of shooting way better than anybody shooting it with the combat sights. Next, I've used Speer bullets from time to time. It's a quality bullet, same as all the rest. It will shoot just fine for you. Do you already reload or are you new to this aspect of shooting? Or are you just new to reloading for the K31?
@@lencac7952 , Been reloading handgun ammo for over 20 years. Wanted to start loading my own precision ammo for .308, .223, so got a single stage press. Split 500 each of 168 gr and 175 gr Sierra TMK with a buddy, so that's what I got. Been looking online and have not seen anyone use the TMK for the Swiss 7.5x55, looks like a similar profile. For powder I have Varget and 4064. Still new to rifle ammo reloading.
Thank You for replying.
@@dlkk2057 Hey DLKK: That's cool. So you have a good grip on the reloading thing. High powered rifle cartridges are a bit different than pistol cartridges. But absolutely the same process as reloading 308 or even 223. I've been reloading high powered bottleneck cartridges for a long time so I've learned a few thing. So feel free to ask questions. I'll help if I'm able.
It would be awesome if you did the same comparison with privi partisan ammo
You full length resized the brass after each firing. That is perhaps the reason for the smoke marks on the cases. Using the same rifle , you only need to resize the necks , not the whole case.
Hi David: Well I have tried that with the same results. The GP11 cases are literally good for only 2 reliable reloadings. However, on K31's I've found that if you only neck size the cases you will have a hard time getting the rifle to go into full battery. And on a K31 that is a very bad situation. I never full length resize fired cases. Only unfired brand new commercial cases. I only move the shoulder back just enough to provide .002" to .003" clearance in the chamber. Keep in mind that factory GP11 ammo. has a datum to base measurement of 1.790". The chamber on mil-spec K31's is in the 1.805" range. So there is an abundant amount of clearance. Probably for service use to ensure reliable chambering of the round in all field conditions. However, that excessive clearance I believe causes the case to be stretched on it's initial firing. And the weak spot is that area where the shell is attached to the cup. Plus one must keep in mind that GP11 brass was never intended to be reloaded in the first place. I have never had the the problem of the shell and cup separation when using commercial brass. Thanks for your interest and comment David (-:
I have to wonder if that brass isn't a lot different. Is that 284 winchester brass reformed? It looks completely different than the GP11 brass. I'd like to see the Horandy bullet reloaded in some GP11 brass and see what it looks like then.
Hey KDESFAN: Nope, no need to reform 284 brass as 7.5x55 brass is readily available.
th-cam.com/video/7ElARA6LlEk/w-d-xo.html
th-cam.com/video/0YoE7mXIqas/w-d-xo.html
Good information
Hi thos: Thanks much appreciated (-:
Very cool.
Great informative video. What was your source for the new old stock receiver and barrel? Thanks
I wonder how much interest it would take to get a company like Hornady or Sierra to start producing GP11 spec projectiles? I know quite a few people who swear by Sierra Matchking bullets for their precision K-31 handloads, but it would be nice to have the option of easy access to original Swiss style bullets when loading for these guns.
Well, I just checked a factory 7.5x55 with a head stamp of NNY, not sure which brand that is but that bullet checks .306". Which is neither commercial .308 or GP-11 projectile. And as a result I would think that the free play would fall somewhere between the commercial .308 and the GP-11 bullet. And I can't imagine that any of the brand names would manufacture true GP-11 type ammunition due to the limited use and what I'm sure would be a very technically challenging on a production basis to produce a bullet with a bi-dimensional bullet. Especially considering the real thing is readily available and very good prices. Plus I have it on good authority that the Swiss still have 10's of millions of GP-11 ammunition in surplus doling them out on a basis to keep the prices fair.
Yeah, that's PPU out of Serbia. They make a pretty good load for the 7.5x55 at a decent price point, nothing to sneeze at but it's not exactly going to be lighting match heads at 300 yards like you can with some handloads and GP11. They're a good source for reloadable brass, but I can never seem to find their projectiles for sale on the US market.
easy enough to get in Europe I've used them for years, work pretty well
look for PPU .308 174grn bullets, they are copies of the GP11 bullet
Hi Ken: I have dissected a couple PPU clones of the GP-11. It uses a single dimension .306 boolit. Not a stepped dual dimension boolit like a real GP-11.
so is the goal to have the bullet not touch the lands but also not be too far away? im curious to know what the range to be in would be thanks.
Yep, the theory is that if seated close to the lands it will provide slightly better consistency in regard to accuracy............... theoretically anyway. Keep in mind how seating depth from the lands has a direct effect on spike-pressures upon initial ignition of the powder. Most mil-spec rifles have bullet free-play in the .100 - .125"" range. GP-11 ammo. in a K31, due to it's .306" dia. bullet has a conventional bullet free-play of about .125". So I'm not totally convinced that seating the bullet close to the lands is always an absolute path to better accuracy. I think there is many other variables that make it difficult at best to say that. The actual construction of the cartridge is one of those variables. Unlike all other mil-spec rifles I load for I am finding the lands in order to move the bullet out closer to the lands. However, on the K31 because it was designed around a .306" bullet I find the lands so I can make sure the .308" is seated far enough into the case so there is no interference bullet to lands. My preferred bullet free-play for a .308" in a K31 is .025". Keep in mind that different bullets will check different due to the shape of the nose.
Lencac. I wonder if a company like Corbon would make sizing dies to reshape and resize the .308 bullet to a new dimension of that of the GP-11profile? I would believe that the bonding would be an issue with the tendency of spring back in the copper Jacket of the .308 dia bullets being resized, What do you think? Dave.
You mean like a set of swaging dies? That would be doable, but you'd really only be able to swage out single dimension projectiles like reducing the max diameter of a .308 to .306 or down to .304, but I can't think of a way to swage out a dual-dimension boolit like the GP11 projectiles. The simplest way I can think of bubba'ing together something like that would be to swage it down from .308 to .304 and then try to add a .001 belt of copper shim stock to the jacket to bring the total diameter of the belted portion closer the the base just ahead of the tail up to .306. But all I can picture is horribly wonderful slow motion trainwrecks of the belt material shearing away upon firing and getting stuck in the barrel, eventually causing either the breach to fail and blow the center bolt backwards out of the locking sleeve or just pop the top of the chamber open with excess pressure generated from the partially obstructed bore.
Well it's an Idea I had. Some how they did it, So it must be a doable thing with the right Dies and Press. Like you said, with the belt thing, Pop go's the weasel and that's the end. That isn't for me.
If swagging is the course of action then it would require a 2 swagging die set. First swag to do the front of the boolit to .302" and the 2nd swag to do the back end of the boolit to .306". Why can't we just get the GP-11 projectiles? Oh wait, that would be a Catch 22. if we did that and went to all the trouble of doing that and reloading GP-11 projectiles the perfect result would be GP-11 ammunition. So in spite of my new revelation about GP-11 ammo. I'll just keep loading .308 boolits and calling it good :)
You may have covered this, if you did I apologize! If you measure the GP 11 ammo, measure it from the base to the ogive, then use that measurement and produce a Hornady 178 round with the same measurement. You will end up with 2 rounds with 2 different bullets having the same measurements (over all length does not matter) what do you think?
Lencac in your opinion what hunting bullet best replicates the GP11 ?
have you thought of having a machinist grind the tips / alter the original w/o taking it apart?.......if you do that and try it I would love to hear the results of interesting flutes and hollowpoints
Hi Brian: Well, I don't hunt so my opinion is only that. But I would think that any of the brand names in ballistic tip in the 175gr to 180gr. should do the job nicely. And I'm pretty sure Privi and perhaps Tulammo make commercial hunting ammo in the 7.5x55 cartridge.
Excellent info 👍
Thanks Johannes (-:
Brilliant work
Thanks Jeff :)
Why are Swiss rifles and pistols so accurate?
(imo the world's best surplus rifle and pistol are the K-31 and the P-210.)
Because we can.
Excellent video!! Thank you!!
Do I need a K31 ?
well duh ........ of course you do!
great video and invaluable research for noobs like myself!
You're not a noob Rock .................... let's just say ballistically challenged enthusiast ;)
lencac haha I appreciate that
Very interesting, I wonder if you were to take a GP-11 bullet and load it into a 7.62x51 case (if it would chamber) if it would be more accurate
more accurate 7.62x51 round shooting out of a .308 rifle
That's an interesting thought. I suppose a person would need to do that to at least 100 rds. with different types of powders and charges to really start to get a decent understanding. But it would not surprise me at all if the GP-11 projectile did in actuality prove to be somewhat superior. So in light of that here's a story from an article I read years ago. Perhaps in the American Rifleman but not sure. Anyway, it said that at one time, just prior to WWII the US military was experimenting with the GP-11 projectile in the 30 cal. Browning machine guns. And if I remember correctly they gave 2 main reason why that projectile was rejected. One, because of the GP-11's very high BC they discovered some of the bullets were flying beyond the training areas. And two, which because of the same reason, all the sighting systems on anything that projectile was shot from would have to be completely recalibrated. Which obviously would have been a considerable undertaking.
Maybe a test for the future?
Also do you know what powder is most similar to the powder used for GP-11?
I would do a test of that provided I had 100 GP-11 rds. that I felt like I could spare. Donations?
Would it be safe to unload gp11 brass and reload using the same powder PLUS extra for a hotter load?
I'd like to get the gp11 projectile going at 2750 fps.
Also how would you pull the gp11 bullets?
Alex: Can't say if it's safe or not. That one is on you. But probably not. Use a collate type bullet puller. However, I'd be curious to see how your experiment comes out for both MV and accuracy.
Not a good idea. K31 straight pull action, not a Mauser. You don't have the camming power of a turn bolt for extraction of fired cases. If you go higher pressure than GP11 you will likely run up against extraction problems.
This again. K31s have better camming than any Mauser. The K31 has helical locking lugs. During locking and unlocking, the bolt travels approximately another 1 mm. This is what gives you primary extraction and a vast mechanical advantage. I would abstain from such experiments because I don't see any benefits from tampering with match grade factory ammunition in a rifle that has not that much of a safety margin, and powder with properties unknown to you. Additional video on primary extraction in Mausers and K31s th-cam.com/video/ZFqOK843IyU/w-d-xo.html
@@Haaraff , ok where do you buy GP11 ammo from ????
@@MegaBait1616 depends how much you want to spend. You can find it online for about $1 a shot on Gunbroker and Eidelweiss Arms. Other than that you have to get lucky at local pawn shops or gun shows. I have found a few boxes here and there for $7 per box of 10. I saw a guy at a show selling some for $5 a box a few months ago but was so broke I could only buy one box and know I would probably never see that great price again. Good luck.
TY :)
Sellier & Bellot 7.5 looks more like the .308 and does not have the different form. The S%B shoots well. Probably you have the real military gp11 here.
Yep, the comparison is with a GP-11 rd.
Double diameter billets have been around for a long time.
Hi Aaron: Interesting. I didn't know that. The GP11 bullet is the only one I've ever encountered. Do you have any idea of who else used that type of projectile? My understanding is that RWS makes those. So I suppose they might very well have used them in other European cartridges too. Thanks Aaron for your comment and time spent watching (-:
There were paper patch bullets like that. I can see the black powder cartridge that used a DD bullet but I can’t remember it. When Winchester introduced the 264 Win Mag, it had a double diameter bullet. Above the cannelure the bullet is .258 and below it’s .264. All of us who hand loaded the 264 had to ream .080 (80 thousandths) out of the lead to seat .264 diameter bullets out properly. You have to seat the .308 bullet way to far past the neck of the case to chamber the cartridge. That will destroy your accuracy. I looked at you measurements. If what I observed is correct, you should ream approximately .120 (120 thousandths) out of the throat of the bore. Triple check your measurements again before you ream the throat. This, like the 264, will allow you to seat the .308 bullet out properly, greatly improving your accuracy especially at distance. Using the DD bullets after reaming will not affect your accuracy very much if at all. It will simply create a Weatherby type lead that the bullet can jump. Just to reassure you, I’ve seen barrels on high power varmint and target rifles with 3 to 6 inches of lead burned out of the bore, and they grouped the same as new. I have a 22-250 with about 3 inches of rifling shot out of the bore. It still shoots 3/16” groups. Oh yeah, I think that Italian Carcano used DD bullets as well. I’ll have to look again. I’m sure there are others as well. I hope this information helped.
@@aaronbuckmaster7063 Hi Aaron: Interesting stuff about other DD bullets. I would think that is more of a European thing. So it doesn't surprise me that something like a Carcano would utilize a DD bullet. However, I did not know about the 264 cartridge. So that's good stuff. Thanks.
I used to do restorations on Swiss K31's. And I've done a bunch of those for people. As for accuracy when using .308 bullets I would seat the bullets .025" off the lands and the accuracy was excellent.
Here's a link to a typical range test of a K31 I did a restoration on for one of my YT subscribers. Keep in mind this is not a scoped rifle. I'm use diopter sights for all my K31 range tests. On this video these are my first and only shots I've ever taken with this K31. Mounted the sights, did a by-eye bore sight and started shooting from the bench.
th-cam.com/video/0m5ToK6Nu0g/w-d-xo.html
Good conversing with you Aaron. Be cool and be safe brother.
The GP-11 bullet dates back to 1911, unsurprisingly.
It has a secant ogive, unlike, say SMKs. The Hornady also has a secant ogive BUT it has a distinct parallel section, whereas the GP-11 is utterly fifferent.
The 1911 rifles and carbines have LONG throats because the had to be able to work with this slinky new bullet, AND the millions of rounds of the earlier, round-nosed GP-90-02.
The K-32 and the later Zfk-55 sniper have a VERY short throat to derive optimum performance from the GP-11 bullet. Bullets with TANGENT ogives, like the Sierras, will jam in the start of the rifling before the bolt can be closed.
Hi Brucein Oz: All good points. Although I must stress if you load commercial bullets with a minimum of ogive to rifling clearance of .025" you won't have an issue with chambering or ejection. Provided the cases were sized properly to start with.
@ScottLeonard
Its pronounced o-jive
Hi MClick: Thanks for your assistance with the pronunciation of a term I obviously massacred. I hope the content was at least interesting for you. Be safe and have a great day (-:
That infernal music in the beginning of the video made me gave a thumb down