PMAG 30 round mag won't go in after about 60 rounds ?

Status
Not open for further replies.

Wanderling

Member
Joined
Nov 21, 2011
Messages
923
Just ran into a strange issue at the range. I have a relatively new to me AR-15. It came with one Magpul PMAG and I bought another. Both are M3, I believe. The only difference is that one has a window and the original one doesn't.

So, after shooting about 60-100 rounds through the rifle, the second mag wouldn't go in. I mean, it wouldn't physically fit into the magwell until I took a couple rounds off from the top. Then, on another reload, it took some effort to "squeeze" it through. When I loaded it originally, it went in no problem. The original mag functioned perfectly fine all the time.

It's almost as if the working end of the mag got deformed somehow with rounds in it ? Doesn't make any sense. Once inserted, it functioned flawlessly.

I am all out of rounds so I can't test it at home today. Needless to say, this leaves me puzzled.
 
if you have real PMAGs with the cover on top, the end of the cover is designed to be used as a feed lip gauge. (the OEM versions don't have the cover) you can use the gauge to tell if your feed lips have spread too far apart. if you get a different measurement on the good mag vs the bad mag, you've found your problem. (spring pressure on the rounds may cause the lips to spread apart, so measure it loaded and unloaded)

also... if you are new to ARs... it makes a huge difference if the bolt carrier is forward or back. when back, any mag should go in pretty dang easy. when forward, if you are at 29 or 30 rounds, the bottom of the bcg is pushing the rounds down in the mag as you seat it and will always take a lot more pressure.

big question is, are you 100% sure that apples to apples one mag feels different than the other?
 
if you have real PMAGs with the cover on top, the end of the cover is designed to be used as a feed lip gauge. (the OEM versions don't have the cover) you can use the gauge to tell if your feed lips have spread too far apart. if you get a different measurement on the good mag vs the bad mag, you've found your problem. (spring pressure on the rounds may cause the lips to spread apart, so measure it loaded and unloaded)

also... if you are new to ARs... it makes a huge difference if the bolt carrier is forward or back. when back, any mag should go in pretty dang easy. when forward, if you are at 29 or 30 rounds, the bottom of the bcg is pushing the rounds down in the mag as you seat it and will always take a lot more pressure.

big question is, are you 100% sure that apples to apples one mag feels different than the other?

Not when empty and the gun is unfired.

When the gun was hot and the mag was filled it either wouldn't go in at all, or with much pressure. Now the magwell was never hot to touch, so I am sure the barrel being hot had nothing to do with it.

Again, it's not like it would go in a bit and then stop, it wouldn't fit at all. Very strange. I will order an aluminum 20 rd and see if it makes any difference, 30 rd is an overkill anyway.
 
Make sure you're not accidentally loading 31 rounds in the Pmag. 31 will fit with a little effort and make the mag very difficult or impossible to lock into the mag well.

BSW
My friend had this issue with 20 round GI aluminum mags, he was loading from a bulk pack "bucket of bullets" and put in 21 rounds to "fill it". Wouldn't lock in with the bolt forward. Loading the as designed 20 rounds was the cure.
 
If a Magpul won't insert & lock on an open bolt, either the mag is splitting along its seam, or the mag catch is adjusted wrong. That's assuming your lower is in spec.

If the mag is splitting, contact Magpul. They'll take care of you. If the mag isn't splitting, adjust your magazine catch. Back off the catch a little at a time until the magazine will lock in place easily.

If a 30 round Magpul loaded with 30 rounds won't lock in on a closed bolt, the top two rounds are out of place. This occurs with older Magpuls. If this is a problem, contact Magpul. I believe they'll make arrangements to replace the mag with an updated version. Magpul customer service is nothing short of amazing
 
Status
Not open for further replies.
Back
Top