My 7.62 x 39 bolt from model 1 sales broke a lug today, I was not to happy about that. specially since I see others are having problems also.
I am an FFL /SOT and shoot a LOT of FA in M16s. Mostly Wolf ammo to boot. None of my guns, to date, has cracked a bolt. Have cracked one cam pin though.
I am anal about inspecting the bolt and cam pin every shooting day and suggest others do so at LEAST as often.
Obviously, i do not shoot in the miserable conditions that our folks in the sandbox do. Not sure if that has any effect on the bolts but it sure wears everything it gets in (and it gets in EVERYTHING) so can't be good for the bolts either.
I am no engineer but am an A&P dealing with highly stressed parts. IMHO the bolt issue is less one of design than one of quality. I would NEVER use a plated bolt due to hydrogen embrittlement. I would never use a bolt from a questionable source. The type and QUALITY of the steel and in particular the quality of machining a bolt has a HUGE effect on it's strength! Tiny tool marks and / or poor radi can lead to stress risers and cracks. Very highly stressed parts that are "on the edge" in aircraft are beautifully finished, usually polished with generous radius at areas like the base of a locking lug. There is a reason for that - and an associated cost!
I have looked at a lot of bolts at gunshows and in customer's rifles. Some of them are VERY poorly finished and likely to crack eventually, IMHO. I suggest you inspect YOUR bolt and a quality one, such as Colt and decide for yourself if your's is "good enough".
Admittedly a better design, such as the AK is less susceptable to these kinds of problems but we are pretty much stuck with what we have. Until a better design (which would be of the bolt AND barrel extension most likely) we need to deal with it by bolt QUALITY.
just my .02 worth
i cut down that lug on one of my 7.62x39 bolts like armalite did on their 5.56 bolts --so far it ain't broke.
the problem is when you open up the ar bolt big enough for the 7.62x39 rim there ain't much meet left for the bolts lugs to hold to the bolt base.
now that 6mm-ppc bolt is a step in the right direction!
Where did the lug break? Was there a sharp edge where the lug protruded from the bolt? What kind of radius exists at the point of failure (or on the other lugs)?
Did you recover the broken piece?
Was the failure point the only one or are there cracks starting on other lugs or adjacent to the failed lug?
Is the wear pattern on the rear surface of all the lugs the same or are some more "shiny" or the pattern of differing width?
Chromed or no?
How many rounds fired?
Got any pictures??
Any idea who REALLY made the bolt? China? Considering where you bought it, nothing would surprise me.
Cant be China. Illegal too import gun parts from China.
Holy mother of God.
I read through this whole friggen thread and now I am afraid too shoot these damn things. I should have stuck with my AKs.
Just spent an hour getting a fish hook out of my finger. Now all I need is a bolt in my eye ball.
"Man needs but two things to survive alone in the woods. A blow up female doll and his trusty old AK-47" - Thomas Jefferson 1781
I bought a super bolt from AR-Performance last year. The webs on the lugs do look a little larger. Took a couple of months to get it.
the 7.62x39 bolts don't break all that regularly and there the thinnest of the bunch.
one of my 7.62x39 uppers has a couple thousand down the tube so far so good.
i sort of think the spat of bolts breaking in ar-15 and even in some AKMs may be due to just a batch of rotten steel that has been floating around for the last few years.
even though the bolt can't come from china it could be made from china sourced steel!
Chinese marked parts would be illegal to import, unmarked ones trans-shipped through another country with "Made in Taiwan" or similar on the crates would get in. Besides, the PLA pretty much owns a large chunk of the Port of Long Beach, ya wanna bet their "foreign trade zone" warehouses have more than a few naughty things in them that eventually wind up here outside of "normal channels"?
What yaro said... and as for Mod1 bolts breaking they are poor quality no mater where they are made.. you usually get what you pay for.. I've always seen M16 bolts break at the cam pin with the old wolf ammo that was very common.. cause... lugs broke more rarely in the Military.. the M-4 was after my time..so I can't say about them.. but they need a bit more gas to function that a longer barrel gun.. Also.. I believe the MP inspection kept a higher quality parts in Military guns and the rejects went to the gun shows.. B2B