Colt AR 15 A4 lower wont take my mags

[Dave.S]

Hi all I picked up a Colt AR 15 A4 Lower,Its in really good shape but my metal mags wont fit?I have a Dar 701 lower and the mags are fine?Do I need Colt made mags?Dave

 

[badboybeeson]

What mags. And where are they pinned

 

[Power Pill]

probably the rivet

 

[Dave.S]

They are NHMTG S/42 marked Aluminum mags made in Hartford CT They ar riveted at the back,but it seems they are too wide not long.Dave

 

[Leviathan024]

interesting

 

[Power Pill]

They are NHMTG S/42 marked Aluminum mags made in Hartford CT They ar riveted at the back,but it seems they are too wide not long.Dave

They arn't 7.62/308 mags are they?

 

[Stevebot-7]

I suppose it's not impossible they are 5.45x39, or 7.62x39 magazines or even 7.62x51. Can you post up some pictures comparing the magazine size to .223 or 5.56x45 cartridges?

If they are too wide, how much of a difference is there? Can they hold .223 properly? For AR or other STANAG mags, there should be a little extra length on the inside of the magazine body in front of the bullet tip, but not much just a few milimeters really.

Should look pretty similar to these. Otherwise they might be designed for a different cartridge or firearm.

 

[luke s]

Shouldn't need colt mags, any mag should work
Either mags are out of spec or lower is out of spec.
What mags are you using?

 

[misanthropist]

Something's off...NHMTG S/42s ought to be fine. That's a standard GI 5.56 mag made by Okay who also makes Colt mags.

 

[Mirk]

I have heard of a Colt lower being tight with magpul mags, but something's not right here.

 

[misanthropist]

My instinct would be to throw a set of calipers on those mags. It's hard for me to imagine a scenario in which a Colt lower has a significant variance in internal dimensions of the magwell...I assume they mill out a billion of them at a time, and if it slipped in the clamp the whole thing would be screwed.

IIRC the internal width of a TDP magwell is 0.898", +/- 0.015". But I have no idea whether that is pre- or post-anodize, now that I think about it.

I looked around a bit to see if I could find leaked documents on mag tolerances but I couldn't find any. Funny, seeing as the TDP for the M4 got leaked a few years ago.

At any rate my best guess is that you happen to have the first mags that came off the dies, and the last lower that came off the mill, and the tolerances just add up badly.