Colt M4 Destroyed by Over Pressure.....

@RickR
Most of my shotguns are old. So very few issues and some lack a disconnector reset or hold the trigger and they cycle and go bang.
I'm aware of the slam fire issue with the 877 (12/13 to 11/14) and Remington's recall. Mine is an 870 and a lot older.

90 or so times out of 100, operator head space is more the root cause than any other issue. In this discussion, a 300 BO is bad juju when fired in a 5,56 barrel.
As they were inexpensive and I'm frugal; I've modified AK-74 magazines to work with 5,56. The recipe is simple, change the followers and use Dremel to tweak the feed lips. As I wrote 5,56 on them, if there is a problem; guess who created it?

I'm an engineer also who after many years accepted; I can't fix stupid.