Broken or cracked USGI Carbine Bolt

[W5USMC]

I am curious to know if anyone has personally experienced a broken or cracked USGI carbine bolt. If so what was the manufacturer of the bolt and where exactly was the breakage.

Information

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[floydthecat]

I am curious to know if anyone has personally experienced a broken or cracked USGI carbine bolt. If so what was the manufacturer of the bolt and where exactly was the breakage.

N14 right lug thru the extractor pocket.

[mrclark303]

How common an issue was this, or is this more of a 70 years old problem?

[Bruce McAskill]

It was common on the type 1 bolts that an engineering change made the extractor pocket a wee bit stronger in the type 2 bolt. But they can still break and many times from the bolt not closing all the way because of a case being just a tad to long. The pockets the lugs rest in the receiver can become damaged over time. This will hold the bolt back just enough time to cause the bolt to be slammed causing extra pressure to be brought against the right side lug and breaking the lug in the extractor area. The type 3 bolt aka round bolt ( and not the name M2 bolt as it was in use well before the M2 carbines came along.) is still a bit stronger but they too have been know to let go now and then. If one reloads then DON'T push the rounds to the very peak of speed. Standard loads work fine and a 75+ year old carbine will still preform fine. All makers of the typ1,2 and 3 bolts have had breakage. I had a very early Underwood bolt break on me with factory ammo. No reason for it except it was just an early type 2.

[DaveHH]

Bruce covered everything that causes the bolt failure. One thing to know, I seem to recall this coming from BQ, if the failure is a result of a problem with the receiver (damaged slots on the left side, beat up receiver lugs etc.) the carbine will continue to break bolts one after another.
Additionally, the carbine has an Achilles heel, it is cartridge case length. If the case is too long, the bolt will never close all the way. During the manufacture of the 6M carbines, carbines were blowing up at an unacceptable rate. The problem was solved by measuring 100% of ammunition cases. I would check on your ammunition and headspace the weapon.

[W5USMC]

@DaveHH, I don't have a broken bolt and I am not looking for potential causes, basically attempting to gather a little bit of info from any members that have actually had a bolt break or crack on them. Looking for the manufacturer of the failed bolt. Actually hoping to get enough info from across a few forums to dispel any rumors that one particular manufacturer's bolts break at a higher rate than any of the others.

[USGI]

This search might help a bit, or variations of it. - Bob

https://www.google.com/search?biw=15...h1QMIDQ&uact=5

[Bruce McAskill]

There were no makers who didn't have broken bolts. It was considered to be the nature of the beast. But if you want to reduce your chances the use a type 3 bolt. But once again keep a check on the recesses on the receiver for any damage. If found early it can be repaired before damage is done to the bolt. If a bolt has been damaged then the receiver can be repaired. Someone with good machining skills and good welding can do it. If you reload then check each case after sizing and trim. Some carbines need cases to be trimmed each time loaded.

[painter777]

anyone has personally experienced a broken or cracked USGI carbine bolt. If so what was the manufacturer of the bolt and where exactly was the breakage.

Wayne,
Your just asking for personal experience..... Correct ?

2013,
I have had 1 cracked bolt. The previous shooting session I had ran it hard.
About a week later, the next time out before shooting I noticed what I thought was a scratch on top in/around the Extractor. In the sun light and by feeling it from left to right I could see / feel the right bolt lug was cracked.
During inspection at home I could find no issues with either locking shoulder, receiver rails, Op slide lugs or slide tabs. The carbine was well lubed and I had been shooting reloads the last session with all brass being trimmed and loaded with 15.0 of 296. The bolt was a N14 that I believe was original to it. I replaced with another N14 and have continued to shoot this same carbine with same load.

In 2017 I noticed a rifle club member getting ready to shoot his carbine. We talked a bit and I noticed his bolt was cracked the same way. Told him the possible causes and he packed it up. His bolt was also a N14. Didn't know him and have never heard if he found other issues.

Pictures below are from my bolt, his looked just like mine:







I have read and seen pictures of just about every makers' bolts cracked/broken, both round and flat. Breaking the N14 made me leery of all bolts. Breaking one has taught me to note conditions on every carbine I shoot or am considering purchasing.

I hope this helps your survey,

[W5USMC]

Your just asking for personal experience..... Correct ?

Yep Charlie, just looking for the actual members that have had broken bolts, don't need the (I knew a guy whose Uncle said stuff). BTW, I had already noted your experience with broken bolts from looking through the older threads.