Bolt hold open question

[alamo5000]

I am having a very minor issue with one of my ARs. When I get to the very last round in the mag the bolt will hold open. I am pretty sure the issue is narrowed down to a specific magazine but I want to ask and see if there is anything else to check.

If it is a mag what could the problem be? Possibly a weak spring?

Anyway the mag is a 20 round PMAG... I am pretty sure I have it narrowed down to which magazine. Let me know if I need to do anything to fix that mag.

[BoilerUp]

the follower could be binding enough to slow it down if it is dirty on the inside. I have a 10 rd PRI 6.8 mag where the spring actually binds on the waffle pattern and something like the 2nd to last round always misfeeds as a result. I wouldn't expect that on a PMAG. The simple solutions here is to discard that magazine. They are expendable items.

[alamo5000]

the follower could be binding enough to slow it down if it is dirty on the inside. I have a 10 rd PRI 6.8 mag where the spring actually binds on the waffle pattern and something like the 2nd to last round always misfeeds as a result. I wouldn't expect that on a PMAG. The simple solutions here is to discard that magazine. They are expendable items.

My mag is dirty as hell. I don't know the round count but 100% of them are suppressed. I will clean it up and see what if anything improves. If not I have a box with a few dozen more 20 rounders.