What makes the so durable in regards to Bolt life and barrel life? Is it bolt construction combined with a CHF barrel, the low chamber pressure ammo? I’m honestly curious as I have read here the AK is severfold times more durable than the M4, but what makes it so much more durable?
You have 3 massive bolts combined with lower pressures. I believe that is why AK bolts last longer.
Less stress points.
Ian Hogg ( http://en.wikipedia.org/wiki/Ian_V._Hogg ) observed over 25 years ago that the trend toward high pressure fast twist military arms was the wrong move.
It is sometimes said that if you have a big enough engine anything will fly. The success of the 5.56mm says more about the size and power of the US military machine than it does about the technical superiority of the round.
Lower pressure 6mm rounds have been around for over 100 years. The US Navy looked at a 6mm as far back as 1895. The original SAW was slated for a 6mm cartridge. The Brits were pressing for a .280 round and FN originally made the FAL in for this round. Today we have many people demanding the 5.56 be replaced by the 6.8 SPC or 6.5 Grendel.
The 5.56 soldiers on because it has to. It is what we have and we have it in quantity. But as a military round it has a great many issues.
In my opinion, as I have no data to back it up:
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Much more material that has few sharp edges
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Hasn’t been modified to run a shorter gas system/shorter barrel without changing the bolt dimensions.
But even then, they still break. Just not as often as the AR.
I don’t know this for sure, but isn’t bolt breakage more of a problem in the carbine versions of the AR and not really all that prevalent in the rifle length systems?
Still happens in the M16 just takes longer, still no where near the life of a AK bolt though.
All guns break.
I’ve cleared more malfunctions from AK pattern rifles than any other firearm I’ve ever shot. IMO, this has to do with crappy magazines and spotty ammunition. That and their owners never really care for them.
But honestly, I think you don’t read about a lot of bolt breakages and other high round count failures with AK pattern rifles for the simple reason that their owners don’t shoot them as much.
I’d love to see 6.8 as widespread as 5.56, but any other caliber will never get as big without uncle sam placing large orders.
I have a feelig AK owners shoot more than AR owners given prices of ammo until recently.
And of course all guns break, some just break less and I was wondering if it was more design or low pressure ammo. What would an AK be if it ran 63,000PSI ammo like we do?
People do shoot AK’s a lot. Maybe not in US, but then again US is a bad example of AK usage to begin with.
AK doesn’t break bolts because the bolt has absolutely massive locking lugs compared to AR bolt. The strain on the lugs is a fraction of the strain on AR lugs. AK will break elsewhere before the bolt breaks. Infact it’ll be scapped before the bolt breaks. I don’t think there’d be a single case of lugs shearing off the AK bolt from normal shooting of the gun.
I’ve seen more receivers or trunions mushroomed than bolts breaking.
I have seen pics of some Chinese AK’s with sheared bolt lugs, but far more improperly hardened trunions etc.
I would add two more things:
- AK bolt do not have structural weak spot that is most often reason of AR bolt failure - big hole with thin walls for cam pin.
- AK bolt runs cooler so it gets less thermal abuse than AR bolt (in AR it is more pronounced in gas systems shorter than original rifle lenght).
And last but not least, we usually in Poland say that Russian stuff “gniotsa, nie łamiotsa” - in loose translation it means that it “bends but not breaks”. This is how Russians design their stuff.
Makes sense Though I still am not a believe in a few degrees makig a difference. The structural weakness makes sense, part of why LMT and KAC removed those.
I also wonder what running a ak-74 with ammo sporting 63,000PSI chamber pressure would do to it given most their ammo runs at 44,000z
How do 5.56x45mm AK pattern rifles fare? Anyone know what the Israeli experience has been with the Galil?
I consider the 55x series to be AK variants. I only have about 1,000 rounds through my SIG 552, and only about 200 (yep, pathetic) through my 551-2. I’ve had correspondence with a Swiss gent that has several privately owned fullauto 552s. He told me that two of his guns had seen 30k rounds, were rebarreled, but no bolt swapped. I was discussing the issue of bolt carrier failures in the 552 with him and was surprised by his longevity of both the barrel and bolt group. Anecdotal second hand evidence, so take it for what its worth.
Would be interesting to see some dynamic analysis of the AK bolt.
- AK bolt runs cooler so it gets less thermal abuse than AR bolt (in AR it is more pronounced in gas systems shorter than original rifle lenght).
I don’t think number 2 matters. AR Bolts do not get so hot the physical properties of the steel begins to alter.
Just because somethign is hot to the touch does not make it so hot the steel is getting weaker. It is not a linear phenomenon that begins at absolute zero.
We also have second hand reports of 552 failures due to bolt breakage with civilian contractors.
They break in a spectacular manner. Not infrequently. I have had 3 do this. Sub-par metallurgy, high rd ct, and questionable ammo help…
The average user will never see this. Western designs require modular maintenance… eastern designs chug along until catastrophic failure. Soviet era smallarms, jets, etc. all had a finite service life exceeding the user’s life expectancy, in high intensity conflict by… a factor of 4-10.
IMO Chinese milled, Russian, Bulgarian in that order. After that get crap shooty
AK bolts don’t break?
News to me.
Yes, they do break less but for a myriad of reasons:
-Fewer, and thicker, bolt locking lugs take pressure better (arguability this is why the FN SCAR bolts sports fewer but thicker lugs (but not go full-retard like the Sig 556))
-The PSI that x39 gives (especially the commercial stuff) is far less than 5.56N so it stresses parts less
Regardless, broken bolts is an easy issue to avoid if one conducts proper PMCS and follows a parts replacement schedule.
Eye pro useful.
IMO Chinese milled, Russian, Bulgarian in that order. After that you see a variety of oddities.
Maintenance not culturally part of the eastern conscript mentality, or the medieval savages the soviets sponsored. Spare parts blocks don’t come with bulk orders. Shoot till breaky, usually a very long time, discard get another.
I disagree. Western militaries tend to hold the, ‘run it until it’s broke’ mentality too (aside from some particular units) especially regarding small arms.
Yes, aviation fields are more pro-active but I’ve yet to see a pro-active non-special unit in regards to small arms aside from some extremely loose standards (like a 5MOA+ M16A4).