My ARs are finicky with magazines

[Livefreeormass]

So I built my first 2 ARs on a Matrix Aerospace lower and an FMK polymer lower. During the panic months (Jan - April), I got a bunch of different brands of mags. I just tested these mags with 4 snap caps. The Colt, Adventure Line, and Orlite mags all seem to work OK: They seat in both mag wells even with the bolt closed and cycled the snap caps OK. The black aluminum (no name marks) and Thermold mags seat in only with the bolt open, but when I released the CH, neither bolt would completely close. I had to press the bolt lock to close the bolt. When I pulled and released the CH, same thing happened again.

I searched the web, seating seems like a common issue, but no one offered a real cure. My question is, can you modify the mags for them to be used normally? Can you sand or mill them? If so, how?

 

[atilla]

are you dropping the bolt or riding it forward with the CH? have you tried loading the mags to 1-2 rounds less their full capacity to see if you get the same behavior?

 

[Colt Delta Elite]

What is a bolt lock? Try and shoot them at a range don't rely on snap caps to check there function.

 

[P-14]

I agree with atilla: I only load 29 rounds in a 30 and never have a problem seating the mag with the bolt closed. Otherwise, you need to hit the bottom of the mag really hard and then tug on it to make sure it seats.

 

[atilla]

I agree with atilla: I only load 29 rounds in a 30 and never have a problem seating the mag with the bolt closed. Otherwise, you need to hit the bottom of the mag really hard and then tug on it to make sure it seats.

fortunately i know i have pre-ban mags as i unloaded one the other day and i'd stuffed 32 rounds in it somehow.

two extra kill nuggets. yum!

 

[Livefreeormass]

What is a bolt lock? Try and shoot them at a range don't rely on snap caps to check there function.

Bolt catch... My bad. OK I'll try with real rounds at the range. But it was kinda obvious that these mags behaved differently.

 

[Livefreeormass]

are you dropping the bolt or riding it forward with the CH? have you tried loading the mags to 1-2 rounds less their full capacity to see if you get the same behavior?

Riding with the CH. The bolt catch still got engaged, so I had to manually release it. I'll try your method at the range.

Sounds like you folks don't have my mag problem though.

 

[Golddiggie]

I had issues with e-lander mags in my DPMS carbine. Got some bs comments from Mako Group about the mags being milspec and the carbine not being (for the reason). Never mind that every other mag worked without issue.

If you have a set of calipers, try comparing the dimensions between the ones giving you issues and the ones that are good.

BTW, I have some 'pre-ban' 20 round (military issued) magazines that have zero problems with my AR15. It's one of the reasons I called BS on what Mako tried to tell me.

 

[Gammon]

I ahd a similar problem with one of my ARs. It performed flawlessly with old GI mags and then refused to reliably chamber a round from a 30 round Magpul, even after I had removed five rounds. The problem was the upper, it was not compatible with the newer Magpul mags. I solved the problem by removing about ten thousandths from the upper surface of the mag catch. This improved feeding and made it easy to seat a fully loaded mag with the bolt closed. If you try this mod, be sure to buy a replacement catch just in case.

 

[atilla]

Riding with the CH. The bolt catch still got engaged, so I had to manually release it. I'll try your method at the range.

Sounds like you folks don't have my mag problem though.

yeah, give it a shot at the range first with a full mag and don't ride the CH. if it still binds up then remove a few rounds and try again, and yet again: don't ride the CH. also spray in some extra lubricant for shits and giggles since this is a new build, right?

 

[mac1911]

Mag testing is a must. some will work and some wont work as well. I have come to like old 20 rnd usgi mags.
all the ones have have puchased the worn ones work best!