Mechanical Nerdery: Front vs Rear Locking Bolt Throw
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- เผยแพร่เมื่อ 9 ก.พ. 2025
- In response to some very virulent comments over the years, this video rather proves that point that the bolt throw on a rear locking rifle can be shorter than on a front-locking rifle, aside from a couple of exceptional cases...
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Lee Enfield No.4
SMLE
Mauser 98
Kar98k
Kar98
98k
Swiss Schmidt Rubin 1911 k11 g11 g96/11 96/11 k31
M1 Garand Carbine M14 BM59 Beretta BM-59
AK-47 Chinese Type 56 56-2
FN FAL L1A1 SLR BSA
Krag Jorgensen 1893 1894
More Nerdery please 😁
The survival of those Bic mechanical pencils never ceases to amaze me. I think they stopped making them in the mid 90s, they were intended to be disposable, but keep chugging along.
They're awesome things!!!
Well I still buy new ones from time to time (usually when I lose them), so i would guess they are still produced
Its cool that thy seem to be unchanged for decades though
When it comes to mechanical nerdery, the Bic twist style mechanical pencils are near the top of the heap. They do what needs to be done with the least amount of effort and complexity. I have several dozen in my ITEOTWAWKI supplies along with many thousands of pages of loose leaf college rule paper and a small ammo can filled with dice...
If you break the tip off and wrap a rubber band around the clip a few times then put the other end of the rubber band around the eraser you’ve got yourself a BB gun that will crack an old school glass computer monitor
@kirikou cortex thanks! I hadn't seen a new one in decades and assumed they weren't made anymore. Nice to know they're still available.
Please continue the Mechanical Nerdery, I cannot get enough of it.
I own three of the firearms you showed and three you mentioned, SKS, K98K, SMLE, M1 Rifle, M1 Carbine, M1A variant of the M-14 and Mini 14. I find this kind of deep dive very interesting. Thanks.
Nerdy? Maybe. Interesting? To we gun-cranks, yes indeed. Carry on, Bloke. You and Chappie are always entertaining, as well as informative.
The other point I would make about rear locking is that you end up with clearer access to the breech face making it easier to clean. Getting kack out of forward locking lugs is a pain leading to all sorts of "French tickler" * cleaning brush designs, that never seem to work..
* Yes I know this is a bit of an ancient term.. ask Grandad (...or even Grandma!)
That was one of the criticisms of the P14 vs SMLE - a pain to clean in comparison. The receiver is full of little corners too.
Negative thing with rear locking rifles is that the cases tend to stretch more in high pressure loads.
This might not be a issue with combat rifles that shoot a round once - but for owners of hunting rifles with rear locking rifles it can wear the cases alot.
Examples of this is the Anschutz 1430-32 - 22 hornet, 222 etc. Or like my german Voere Vöhrenbach in 222 rem. It also came in 222 rem mag, so the system is strong but locks in the rear wich tend to stretch the cases a bit more then a front locking like a rem 700
Same applies to the AR , it's a black hole in there past the locking shoulders .
The flip side of this is that it's much easier to get them dirty in the first place, being more exposed the action is much more vulnerable to jam up from external dirt or debris (compare InRange Tv mud tests of the K98k and Enfield - the Mauser did considerably better).
@@fox-3407 Service guns always get dirty.. I would suggest the easier and quicker it is to clean is the key attribute...
"I've got basically almost all the pink bit in there" oh my.. didn't realize this was part of the Strip series!
Taking the tops off as well, oh my!
Nerdery is never pointless
I own a Swiss 1911, yet have never handled a K31, I always just assumed they shared the same action. Thanks for the corrective nerdery. Cheers
Interesting indeed. The Krag, of course, is well-known (at least among Norwegian sport shooters) for being very sensitive to moisture or lubricant on the casings, which will apparently cause POI-shift. This is, allegedly, a result of the single locking lug.
While there's no question that rear-locking is faster, the questions I'm left with are "how much faster" and "is the difference great enough to provide a significant advantage". To the latter question, I suspect that the answer is "no".
In terms of speed I am sure that there is no practical impact on a combat rifle in a large scale.
The bigger impact would be if that little bit is enough to allow you to cycle the action without loving your head. The Bloke has a video or two showing the impact of that.
Speed isn't the question. Smoothness from the arm and hand's arc of motion is. Smooth is fast.
Fwiw, the U.S. Krags were always renowned for their smoothness, and as stated, smooth is fast...in the right hands.
... perhaps the cause of them having a reputation for breech explosions? We have had a couple of these in UK in the past decade, although one was probably down to muppet reloading..!
@@felixthecat265 the Krags you mean? If you run a Krag in 6,5x55 with a modern load, you will get breech failures sooner or later. Most reloading manuals won't tell you, but your starting and ending loads can be wildly different - to the tune of your max load for Krag will be the same as your min load with the same powder for ordinary use.
Smooth, on its own, is not fast. If you don't complete the quote, the takeaway can be VERY different. The quote - as it was taught to me back in basic training, as well as on numerous other occasions is "Slow is smooth, smooth is fast. Speed is the economy of motion."
The garand action compared to the FAL is even shorter when you consider the cartridge length as well, 7.62X51 for the FAL, 71.1mm overall length, vs .30-06, AKA 7.62X63 with an 85mm OAL in the Garand
It's so simple the smle is the finest battle bolt action EVER made
A great visual example of the front locking lug bolt action is a Sako Lappalainen target rifles. They have an open top receiver ring (ie exposed lugs like an M1) so you can see the extra bolt travel required by a front locking system. Too bad it’s so hard to find good pictures of them.
Your point about the M1 Garand is very interesting. I had no idea the lugs were so exposed.
So is the back half of the operating rod which typically is hidden inside a handguard/forend.
Nerdery is the best type of content.
Can you talk more on the "compensation" effect of rear locking actions, particularly enfields? Is it legit? How can it be proven out, imperically?
Yup, that's a whole topic all of its own :) They made lots of measurements of it back in the day, so it does appear to be a real thing and not just perception.
You always bring me the best nerdery.
I dig the nerdery. As I don't own a FAL in any of its variants (someday!), seeing the overall length difference between it and the M1 Rifle was a bit startling. Especially when the M1 was built for a cartridge with ~12mm/0.5in less case length. And some of the FAL early variants were intended for something like 7.92x33 Kurz or possibly 280 British.
I'm very pleased by such nerdery.
And the rear locking lugs can allow the bolt handle to be far enough Bach to align the hand with the trigger position. Which is probably the larger component of the swifter loading, closing and firing time reduction in this comparison.
Not sure it's the position of the lugs that has an infuence on that, and in any case the bolt handle can always be raked backwards or doglegged (e.g. P14/M17) to put it in that position.
Thank you for the morning Geek Out! It was most appreciated 😁 More nerdery please!
Another great bit of technical insight from The Bloke!
I really like these videos actually. Please keep them coming!
I liked the bit at the end where the cobweb was flapping from your camera. Nerdy spider?
Well I just learned so much in 8 minits more please
I never thought about your point here. Lever action rifles generally have shorter actions than bolt actions. I knew that but didnt ask “Why?” At least in part, it’s because lever action rifles typically lock up the bolt behind the open breach, not in front of it.
The Browning BLR is an exception because it has a rotating bolt that engages with a barrel extension forward of the open breach. The lever throw isn’t exceptionally long only because of the gearing in the rack & pinion action.
Thank you
Excellent explanation. I really like your K31.
Nerdery and breakfast - What great way to start Friday 🙂
Dear Bloke, good point. i hope your Chanel won't be strike because of a bolt action removal.😉. take care
especially for a negligent removal...
Not at all pointless, and especially interesting to see the self loaders too, I'd never thought of them as font or rear locking before this video.
Nerdery is never pointless. you never know when it may come in handy. Normies love to hear things like. It´s od that both P38 and MP 40 shows up in raders of the lost ark. as the movie Is set in 1936. I think they would be happy to hear about locking mecanisms and bolt throw :)
When Bloke 'got almost all of the pink bit in' I was done! That wasnt the sort of nerdery I came here for 😉. Please keep up the excellent work.
Nice explanation of an interesting difference between actions.
More Mauser nerdery please. So many design variants and improvements branching out from the basic 98 action.
Another example like the Garand is the vz. 58, but with a falling block locking system.
Very good nerdery. More please.
To add to the nerdery, a typical bolt action compared to the straight pull of a Schmidt Rubin/K-31 must consider the changing of direction on a typical bolt action when comparing the amount of time to eject the spent round and chamber the next round. In the typical bolt action the process is started with an upward swing of the bolt, perpendicular to the length of the rifle. That motion completely stops once the bolt finishes the travel to enable the bolt to now be pulled rearward. After pulling rearward the direction changes 180 degrees until the round is chambered. However, the action is not yet done. The bolt now must be rotated downward until the bolt is locked.
This is the reason for the design of the Schmidt Rubin. Eliminating the manual perpendicular actions of the bolt provides for a faster ejecting of the spent round and chambering the next. A slightly longer pull, however, is negated by not having to make any perpendicular motions of the bolt action, thus saving that time and more.
It is interesting to see the different designs and the different locations of the chamber in relation to the magazine locations.
3:37 Great now I got that stuck in my head.😄
This is exactly why I am here. For this kind of nerdery.
So .308s are Gare ands and the .30-06 is a Ga-rand. I've finally learned the difference, thanks very much. Front Locker- Ol' dad trained on the 03 Springfield and carried a Ga-Rand. Nerdery is knowledge!
Mah Dad carried an '03 on Navy landing teams, around the Solomans in '42. Right up to when the Nips sunk his ship... oopsie....
You missed the video where he showed a block inserted at the front of the Garand's magazine to prevent the 30-06 cartridges from being inserted. The .308 cartridge is a bit shorter.
I can spend all day reviewing differences in bolt design and locking surfaces. And I have.
Loving the nerdery
Very interesting buddy! I have firearms and never thought of that 🤯 very interesting 🧐 thank you for that!
That was actually quite interesting.
What is supposed to be wrong with rear locking on the lee system they staid in service with the British for nearly 100, years without any falling (life the Ross) were used for match shooting and remained as sniper rifles until the accuracy international replaced them? Sounds a bit like head space!
TH-cam: this video has been removed for a violation of our rules. We don’t know what rule because we don’t understand what the hell you’re on about but it must be bad as gun...
God save the World from all electronic busy-bodies.
Freedom begins when you tell Mrs. Grundy to go fly a kite...
Nerds of the world, unite!
Front lockers are also harder to tel if clear. Once pulled a Mosin nagant out the safe. Pulled it out, Opened the bolt out of instinct and out popped a live round!! I’m pretty sure I looked to see if it was unloaded from its previous range trip. But In a front locker a round can be in there and it can be hard to tell with the chamber so far into the action.
Maybe it's just a mil training thing, but in my short conscript time ages ago, we were taught to use our little finger to check the chamber in the dark or when there is no clear path of sight.
And while i don't have to do that with my firearms as i tend to have good light and a clear path of sight, i would still do that if conditions were different.
@@nirfz Was it true that to prove the barrel was empty at an inspection you stuck your thumbnail in the breech and pointed the rifle at the sky?
If nothing was shining on your thumbnail then the barrel must be blocked by something
@@myparceltape1169 With inspection you mean to show empty to a superior right? Well that depended... I remember instances where (with good light) mentioning the condition of the rifle while having the mag removed and the bolt locked back before handing it over to the person was enough. (as the other person then was able to see or check/feel with the finger if empty) And yes usually the barrel pointed upwards and in a safe direction.
In most instances we removed the mag, locked the bolt back and took out the barrel and showed the breach-end of the barrel. My issue rifle was an AUG, so taking the barrel out takes less than 2 seconds, and you can then easily show the chamber to the other person. (As long as the cartridge casing isn't painted black you could see the colour difference on the end of the barrel even in really bad light conditions)
The finger check i mentioned was a safety check for ourselves when taking apart, checking or unloading any firearm. (MG, pistol...)
Oh and we used the pinky finger because the thumb would be too wide to get in there with most firearms. (and the pinky is the least important if you do something wrong and squish it ;-) )
@@nirfz Thanks. I had never thought of a barrel being so easily removed.
The thumbnail idea was simply to show that light could pass through the tube without any risk of something coming up to hit you in the eye.
But as you pointed out, darkness would nullify that idea.
I have always wanted a Remington 788. It has 9 rear locking lugs in 3 rows of 3 lugs and only needs a 60 degree bolt throw. I want it for its oddity.
Interesting, how would a rear locking straight pull do for speed?
Mannlicher 1886 called :)
The comments I had most often read about front v rear lugs was safety in the event of catastrophic failure; the front lugs with the recessed chamber providing extra protection. I'm not taking sides, just mentioning what has been mentioned elsewhere.
ANOTHER layer of nerdery...The AK bolt was influenced by the Garand bolt.
Except that front lockers tend to fail catastrophically since the locking recesses give a large area over which the escaping gas can act (hence all the clever gas handling on a 98 Mauser).
@@BlokeontheRange Thanks!
Maybe discuss implications of lock on open v lock on close.
Got that planned :)
Now do the Madsen LMG!
I was cleaning my vz 58 after watching this and thought wait, this isn’t front or rear locking either!
A tangantial question: in the days when Target Rifle was still primarily shot with the Lee (in England), were the competitors hand-loading or using factory ammunition? Because to my mind the Lee is clearly the better action for a service rifle, but I am convinced it reduces case life when reloading?
Factory ammunition, issued by the competition organisers. It's only more recently that handloading is permitted in *some* matches, but the big ones are still all issued ammo (which is made by GGG and loaded with 155gn SMK's these days)
@@BlokeontheRange thanks Mike. Here in South Africa, those days are long past. So here pretty much all match shooting is done with handloads.
Always issued ammunition, donated by a grateful government would you believe! How things have changed!
Don't forget that Mk7 .303 was loaded with Cordite and the cases were Berdan primed. Not really something that was easy to handload as the Cordite was actually loaded before the case neck was formed! Mk8z ammunition, which was manufactured to extend the range of the Vickers gun was loaded with NC powder and used a boattail bullet. The aim was to improve the ballistic performance by reducing base drag when the bullet went subsonic around 1000yds. I believe the reason for switching to NC powder was an attempt to limit throat erosion which is a bigger issue with boattail bullets because of gas wash on ignition, particularly with hot Cordite. The Mk7 ammuntion used a flat base bullet.
Today's Nerdy Note.. Most UK ammuntion was loaded with Cordite up to the 60s. Exceptions to this such as the use of NC powder and Ballistite was indicated by the addition of "Z" to the nomenclature, hence Mk8z .303 and Mk2z 9mm ammunition.
There was a ban on the use of Mk8z in rifles leading to the myth that it was "more powerful" than the Mk7. This was untrue as the real reason was to improve long range performace in machine guns, which were typically used at ranges over 1000yds for "harassing fire" and for sweeping dead ground. Mk 7 bullets tended to go unstable at transsonic velocities, limiting the range and reducing the accuracy. Nevertheless, large numbers of infantry would "aquire" 8z ammunition to use in "special occasions". The main reason for not using Mk 8 in rifles was that it produced non standard wear and the sights were not regulated for the round.
Regarding case stretching.. never found it an issue, and I have been reloading .303 for years!
@@felixthecat265 we used to get government-issue ammunition for target shooting as well (what is known here as "Bisley shooting"), and also .22 rimfire ammo and rifles for school-kids. This ended somewhere around 25 years ago.
Neeeeerrrrd!
Très intéressant
Still waiting for the nerdery on the 303 rim profile🤓🤓🤓
A jungle carbine in 308 would be nice though I dont know if it would sell tbh
Nearly bought one back in the UK, back in the day. Built on a No.4 receiver IIRC.
@@BlokeontheRange I mean do you think people would buy a enfield built for .308 in the carbine form or not worth the investment
Presumably the M1 had very pronounced recoil from the bolts extremely short throw ? I'm assuming its velocity upon impact with whatever stops the bolt would be substantially higher than the Chineseium example?
Is the No. 4 stronger by much than the No. 5?
I don't have one to look at, but IIRC no material was removed in any critical areas, and in any case a No.5 action is still much chonkier than an SMLE or Long Lee.
i didn't here if you said it actually made a difference or not. Take the bolt closing speed and add or subtract the time for that extra distance is it a significant change over a mad minute. I feel we are talking a total of a couple of seconds in a mad min.
Not to be to pedantic, but I think this presentation is a bit more Geekery than Nerdery. But by avoiding any Japanese rifles, you've avoided Otaku-ery.
I'm super jealous of your fal. Do you have a G3 or a variant of it?
I don't, sorry
It's most important that you get the pink bit as deep as possible 😜 ooh matron!
You, sir have a dirty mind...keep up the good work! 😉
But the K31 is a faster action because it is a front locking system. The rear locking system on the G11 causes the bolt to be a mile long and makes your stroke that much longer.
I just measured, at the cocking handle:
K31: 11.9cm stroke
K11: 11cm stroke
@@BlokeontheRange really? That's interesting it always felt clunkier working the 1911 action it always felt longer. I stand corrected.
I like it when you talk physics and math to me, you nerdy bloke you 🤓😏
So 15mm (or so) of difference in bolt throw is significant because... ?
Time = distance / speed ;) And that 15mm might be the difference between having to move your head out of the way of the bolt or not...
@@BlokeontheRange Moving your head out of the way is also a function of stock length (length of pull) and bolt throw angle, but the distance/speed equation is pretty much the same (for all practical purposes) for 10mm or 20mm. Can you measure the time differential between them? Or is it just a theoretical difference? I just don't see it as significant.
The old Mad Minute results from the early days of the channel had Kar98k splits about 30% longer than No.4 (admittedly there's more going on than just the 15mm or so) but every little helps.
@@BlokeontheRange I admit that 15mm is 15mm, but I suspect that quality of machining and/or angles of throw are at least as significant as length of throw. However, since I'm not qualified, able, or clever enough to test any of these hypotheses, I'm just going to thank you for your nerdy devotion to the hobby. 😀
@@siestatime4638 Are you saying that the Lee is better machined than a Mauser!!!!! The wehraboos will be after you 🤣
Neat
You won't stop the virulent comments with facts and explanations, they expect a loud, angry rant.
The Mauser bolt wobbles through its tunnel, plus its controlled feed both slow you down, its potentially stronger and more accurate front locking is typically is no benefit to the average conscript soldier , it only starts giving benefits with high level marksmanship or with higher power ammunition , the LE was accurate enough even for sniping if tweaked, the actions weren't weak for its designed cartridge , hard to manufacture or heat treat, but easier to clean and clear stopages than the Mauser. In short Mauser actions stink for battle rifles .
On the basis of the stats the Germans provided in their training manuals, an average Gew 98 coming off the production line wouldn't pass the 600 yd minimum standard for an SMLE, let alone a No.4, and the Kar98k sniper rifles had terrible accuracy problems :)
Inner nerd intensifies!
💎
Everyone has their preference, but it really seems that the difference is negligible in actual combat as long as the weapon functions. On the range, or in timed competition, one second may matter, but in the trenches most troops are probably not true experts, may be poorly trained or afraid and are firing as units to just generate fires in support of the machine guns and artillery, who are doing far more damage than riflemen. That could be controversial, but there's a difference between the science/theory and the practical reality.
Huzzah! Nerdery!
Wouldn't the extranerdy question now be: how much time difference those 1-1.5cm of length travel cause vs. how much time difference is between a 60° and a 90° bolt throw in a bolt action? (in % of the cycle time of course ;-) )
edit: or would a 60° front locking bolt even out with a 90° rear locking bolt action? 🤓
With being a shooter I would be curious why the locking position should matter.
I would have imagined that the important part would be whether you can keep the target in your sights while getting the next cartridge in place. Without poking out your eye, of course.
@@myparceltape1169 I think you aren't able to keep the rifle on target with either of the bolt actions shown while cycling without poking out your eye. And while i agree that this would make the biggest difference, in the video he focussed on the speed of cycling the action and the difference due to more travel of the bolt lengthwise.
I do wonder where the whole "rear locking being less accurate" lore came from? I doubt bubba knows about the Boer wars(or that the issue wasn't the action).
Maybe from tilting bolts? Like when surplus SKS and FAL came into the US, being older designs, worn down and/or being rebuilt cheaply and badly. And from there the myth expanded to everything rear locking.
It was floating about already in the pre-WW1 era in the propaganda from the people who wanted the British Army to switch to a Mauser-type receiver, so despite more than a century of being proved wrong, it's still floating about there as common knowledge.
The garand is more side locking in location of the lugs rather than strictly front locking.
No.
I find it rather amazing the places that you're willing to stick your pink pencil, it's almost as though one was watching the OG finger wiggle!!! 🤠👉
But this nerdery isn't pointless.