A while back, I bought a used Orlite magazine for the express purpose of recreating the picture from the Twilight: 2000 Small Arms Guide.
The ribs on the body of the magazine had been ground off, conventional wisdom says that this is because those ribs prevent the magazine from fully locking.
Except I bought a brand new one to check this and it fits in ALL of the AR-15's at my disposal.
Now I am not certain why they were ground off.
I found an old, archived, thread from Arfcom that warned against grinding them off because the feed lips would rid too high and cause the bolt to chew up the none-too-sturdy feed lips.
I bought it for the LOLs, not for serious use so I can give that a check!
I have a bunch of early PMags which have a similar rib. Before I replaced most of them with 80% lowers I had a bunch of Essential Arms J15 lowers which had a mag well that while was technically within allowable spec, and worked fine with all metal mags and most other plastic ones, the Gen1 PMags would not fit, at least not without applying excessive force to insert. Some ARFCOMers said back then that such lowers weren't in spec because ALL mags wouldn't fit, but to counter them I noted that all subsequent PMags reduced the size of the rib, and that in my opinion it was the mags that were out of spec more so than the lowers. Anwyay, the 2nd six pack of lEA owers I bought were J15-2. which had a much more aggressive mag well bevel, and they would accept even the original PMags. So I had to at least partially take back to say that at very least both the lower and the mags were pushing the edges of the spec enough that there was overlap that caused the incompatibility. Anyway, I currently only have a couple of the 2nd batch left, so for me it is largely moot at this point.
ReplyDelete-swj
Early EA lowers were out of spec. It is known.
DeleteMagpul did not account for the variations out in the wild with the Gen1 magazines and did with Rev M on.
Some place on this blog I covered many of the differences between PMAG generations.