09-29-2022, 01:37 PM
Stone,
I am more and more leaning towards 52's early unlocking/blow-out theory. If it was in battery there would be more damage to the action - broken bolts, lugs, extension. For sure get a heavier buffer like a H2 but most of all do something to tame that gas. The easiest was is to get an adjustable gas block. Start with it almost closed and open it one increment at a time until it reliably cycles and locks back on last round. Don't go any further. I also recommend a faster powder like 2460 or 2230 (or equivalent).
The action is probably fine but if the bolt no longer fits the NOGO I would ditch it after pulling it apart and keeping all the parts: gas rings, extractor and ejector parts. Obviously start low and work up with the faster powder. When reloading, bump the cases no more than .003" shorter than whatever the spent cases with the new bolt measure. This to minimize headspace to only what is needed to reliably cycle in an AR.
Pashmina,
Yep, this is the most exciting thing to happen on the Forum in a while. A rare mystery to be solved.
In your Blackout-blowout you would have been loading a heavy bullet, say 220gn. Quickload is showing less than 50% case full with 7.2gn Lil-gun and a heavy bullet. Any case with less than 80% full starts risking 'Flash-over'. This is where the rifle in a horizontal position has the powder lying flat to gravity and space above it. A greater than normal surface area of powder is exposed to the primer spit. It all goes off at once instead of gradually and this equals kaboom. So ironically, less powder can actually make it more dangerous. I use around 11gns of H4198 . And pushing the bullet back into the case will remove some excess space.
I am more and more leaning towards 52's early unlocking/blow-out theory. If it was in battery there would be more damage to the action - broken bolts, lugs, extension. For sure get a heavier buffer like a H2 but most of all do something to tame that gas. The easiest was is to get an adjustable gas block. Start with it almost closed and open it one increment at a time until it reliably cycles and locks back on last round. Don't go any further. I also recommend a faster powder like 2460 or 2230 (or equivalent).
The action is probably fine but if the bolt no longer fits the NOGO I would ditch it after pulling it apart and keeping all the parts: gas rings, extractor and ejector parts. Obviously start low and work up with the faster powder. When reloading, bump the cases no more than .003" shorter than whatever the spent cases with the new bolt measure. This to minimize headspace to only what is needed to reliably cycle in an AR.
Pashmina,
Yep, this is the most exciting thing to happen on the Forum in a while. A rare mystery to be solved.
In your Blackout-blowout you would have been loading a heavy bullet, say 220gn. Quickload is showing less than 50% case full with 7.2gn Lil-gun and a heavy bullet. Any case with less than 80% full starts risking 'Flash-over'. This is where the rifle in a horizontal position has the powder lying flat to gravity and space above it. A greater than normal surface area of powder is exposed to the primer spit. It all goes off at once instead of gradually and this equals kaboom. So ironically, less powder can actually make it more dangerous. I use around 11gns of H4198 . And pushing the bullet back into the case will remove some excess space.