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Old 09-17-2020, 3:59 AM
slamfire1 slamfire1 is offline
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Quote:
Originally Posted by ar15barrels View Post
If you look at the AR-15 action in high speed, (several high speed videos concerning bolt bounce are available) you will see that the bolt bounce is FAR short of even the BEGINNING of bolt rotation, let alone enough bolt rotation to actually unlock the lugs.

I find your opinion not to be probable in the OP's closed breech high pressure event.
These OOB's are very rare, but the posted picture, from an Army report, of Army ammunition, in an Army weapon, is not the only one I have heard about, and the explanation fits the outcome. As you probably know, the Army had to spend time and effort finding a buffer design that would keep the bolt closed, in the early stages of the AR15/M16 program. That tells me, even with the "perfected" design, that the bolt and carrier going into battery and staying in battery is not 100%.

The videos you posted are interesting, but they do not encapsulate the totality of human experience.

As another data point, I was pulling a target with a bud who is a Guard at a Nuclear National Laboratory. This facility has nuclear materials, etc, and it also has kill zones. There are areas in which the Guards are instructed to shoot to kill, regardless of who is in there. Several Guards were fired when they did not shoot anti nuclear protestors who were working their way on to the facility. Incidentally, the anti nuc protestors had planned ahead and filled out wills. Anyway, these Guards train extensively with Government M4's and Federal Gold Medal Match ammunition. Anyway Bud said, one of the M4's on the training ground had an OOB with FGMM. So, here is another rare OOB in a Government weapon, with factory ammunition.

AR15 OOB's are very rare in comparison to all others, but I am going to say, they happen and are real. And the OP did say, and did show, a firing pin strike on the primer.

However, I am not discounting an overpressure event. If this were reloaded ammunition, than an over charge would be the first and highest probability event. But, this is factory ammunition. For me, this does fall into my "known unknowns", in that I don't know the process control technology used in the production of modern ammunition. Technology has moved so quickly that they are doing things that are not only beyond my understanding, but beyond my conception. But, conceptually, given a $100 million or more factory, I could believe that the technology is allowing ammunition manufacturers to weigh each primer, weigh each case, weigh each charge, and then weigh each primed and charged case, and reject those that the automation identifies as an over charge. I don’t know this, and I would like to know how they actually do it now. I do have Philip B Sharpe book, “Complete Guide to Handloading” and the 1940’s technology he describes, is so 1940. If the technology supports it, I just don’t see how an over charged case can come off the production line.

So then, the idea you proposed of an obstruction in the barrel. Would there not also be a bulge within the tube?

Last edited by slamfire1; 09-17-2020 at 12:04 PM..
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