Problem with Sterling 40 Round Magazine

[lcarr]

I just bought a Sterling 40 round magazine.  It appears new in an opened package.  Also, it appears to be steel with the hole for the AR magzine catch already in place.

However, it will not insert into the magazine well of my AR.  I have never had this problem with any of several other magazines, so I don't think that my mag well is particularly tight.  

Doing some measurements of various dimensions of the magazines, I believe I found the problem.  Both a GI 20 rounder and a teflon-coated 30 rounder I have are 2.524" front to back.  The Sterling mag is 2.550".  

Does anyone know what the spec for the front to back measurement of an AR magazine is?  Is the Sterling wildly out of spec?  If so, is it fixable?  Does anyone tune AR mags?  Or is it my magwell?  

Lincoln

[erice]

Something is quite wrong here, and it escapes me. I will check with our "expert" on AR magazines and see what the problem is.

Eric

[kurtm]

ICARR:

The only Sterling mag I had was EXACTLY  the same way. it was god awful tight in all my ARs. with some judicious tapping we got it to work great in my brothers Colt, and mine as well but I had traded it to him. I run thermolds and havent had any problems in any of my rifles, and my  brother swears by his Sterling ONCE fit. Good luck.                                            KURT

[lcarr]

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Quote: from kurtm on 12:57 pm on Oct. 13, 2002

ICARR:

The only Sterling mag I had was EXACTLY  the same way. it was god awful tight in all my ARs. with some judicious tapping we got it to work great in my brothers Colt, and mine as well but I had traded it to him. I run thermolds and havent had any problems in any of my rifles, and my  brother swears by his Sterling ONCE fit. Good luck.                                            KURT

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Thanks for the information.  About the Thermolds, I have plenty of 20 and 30 round mags--I just wanted a reliable 40 rounder for 3 Gun.

Lincoln

[erice]

The following was information is from Troy (our magazine guru) RE:  your mag problem...

" The mag in question is clearly out of spec. However, with a vice and some slow, gentle work, it would be a piece of cake to squeeze the mag into the proper dimension. The key is to go slow and re-measure often. You don't want to reduce the dimension any more than necessary.

These types of problems are actually fairly common, and easy to fix. What is difficult (or impossible) to fix is when the mag body halves are welded together incorrectly, leaving the mag extremely wide or narrow, or causing one feedlip to be noticably higher than the other. I generally recommend tossing these unless you are in a situation where you can't replace them. In that case, do whatever you can to get the mag running, as you can't really make things *worse*.

-Troy"

Hope this helps.

EricE