Do the Pmag 40s reliably feed M855A1?

Any mag that reliably feeds will.


But yeah, the 40s are Gen M3 same feed geometry as the 20s and 30s.

As long as it's an M3 mag, it's good. 40's are only M3, if there was a question.

From a self professed decal whore, that one is awesome.  

Awesome! I'm a self proclaimed Magpul whore!
They come up every now and then. Not exactly sure of the event they were given out at.

I think they were from Shot Show 2016.

Inquiring minds want to know where one can find 40 rounds of affordable M855A1 to fill that mag?

Be aware that there might be a problem with the 40R PMags that require a bit of a manual break in.  I just bought 5 of the 40R Pmags and they would not function in 3 different lowers with uppers attached; all three were of different manufacture, uppers and lowers.  BCGs were Toolcraft Nitride, AIMS Nitride, and another Nitride but I won't swear to its maker. The bolt dragged on the feed lips of the magazine and would not go into full lock up if there were rounds in the mag or if you rode the CH down on an empty mag, and no mag would lock in if the bolt was closed, even if empty.  I locked the bolt back, inserted the mag, hit the bolt release about 25 times (no rounds in the mag) and let the bolt carrier slam home on the empty magazine and "wear in" the feed lips.  After about 25 drops, the feed lips were noticeable shaved and little curls of polymer had to removed from inside the magazine body.  After that though, everything seems fine, the mag can be inserted normally when empty and now the bolt slides over the magazine and locks up fully, even if you ride the CH down.  I've never had to do this with any other magazine in my life so this was a new one on me.  I was about ready to send them back but decided to try just dropping the bolt on the magazine when empty.  Shave and a haircut is all it took.

Thanks, everyone!



Good to know.  I'll be sure to test the mags thoroughly.

That’s going to be a problem with your guns. I’ve used 40s in a bunch of Colts and LMTs over the years and zero issues.

I’ve used 40s, with various ammo, in various guns, without a single hiccup.

Yah, sure it is.  You go ahead and tell yourself that if it makes you feel better.

They don’t run in your homemade budget builds but they’re fine in Colts and LMTs but it’s the mags.  Got it.

40s run fine in my Colt, Noveske, BCM, LaRue and Centurion Arms.... never had an issue.

all mine do