Considering that I might only put a few hundred rounds through each gun on a particular outing, and it's likely the gun will be cleaned and inspected afterward, the chances of a failure that will put the gun out of commission are practically zero. It's fascinating that we can chop off most of the lugs and the gun will still function.
It would take more rotation to unlock. I'm not an engineer, but it seems like it would take a steeper cam path and more force to get it turning. I've always heard that was a big part of the AR's secret sauce was the Johnson style bolt.
No, I mean in terms of round counts. I've heard of M16A1s that were rebarreled multiple times without replacing the bolts. Everything I've ever read or heard says that bolt life goes up exponentially with barrel and gas system length.
I thought Chris Bartocci had some information on this awhile back. Why the bolts were braking and what Colt did to fix the issue. And wasn't that about the time Karl Lewis developed the LMT Enhanced Bolt?
The first 11 minutes discuss the issue.
Last edited by prepare; 11-03-19 at 03:19.
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I am surprised nobody has brought up the KAC E3 bolt. The lugs have been re-designed to reduce the stress at the root. I have seen figures before and “heard” that the E3 has never experienced a broken lug (no evidence that I have seen/read).
ETC (SW/AW), USN (1998-2008)
CVN-65, USS Enterprise
Not really. The form factor and design of the 416 bolt is basically identical to a traditional AR15 bolt in the locking lugs, extractor, and cam pin. The diameter is maintained as no gas rings are used, but that added diameter is in a non-critical area. The 416 has also suffered from cracked locking lugs. This was reportedly limited to a particular heat treat of a particular date code. A friend has sheared lugs from two separate personally owned 416 uppers (not mr556).
SLG Defense 07/02 FFL/SOT
They are nice. Another interesting enhancement is the standard LMT bolt, which has an annular groove cut circumferentially around the bolt head at the base of the locking lugs. It acts to decrease the stress riser that results from (nearly) 90 degree cuts in this location in a traditional bolt.
SLG Defense 07/02 FFL/SOT
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