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Posted: 11/3/2004 10:48:19 AM EDT
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I just finished my first AR build. I have owned several before, but this is the first one I've built. Everything went together fine (except one pivot pin detent that is now in a low earth orbit). I have one small problem. The mag well seems too tight. I have tried 2 different USGI mags and both are tight going in and have to be pulled out when the mag release is pushed. I do not believe it is the mag catch causing the problem because I feel the tightness even when the mag is completely below the mag catch. This was built from a Bushmaster stripped lower with an RRA lower parts kit. The upper is a Bushmaster M4A2 and the stock is a fixed tele-style (for now). Any suggestions on how to remedy this would be greatly appreciated. |
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I don't remember where I copied this from, but it's on my laptop files of FAQ: As documented in The Black Rifle by Stevens and Ezell, the mag well is one of the more interesting areas of the AR-15-type lower receiver. The mag well early on was not gauged or controlled closely, which led to difficulties when a 30-round magazine was required. Consequently, magazine wells vary from manufacturer to manufacturer. A quick survey of several AR-15-type rifles, using a Colt 20-round 5.56mm magazine as a gauge, showed that a DPMS lower had the "loosest" fit for the magazine, with Colt, Bushmaster tighter in that order, and the tightest being several Fulton Armory FAR-15 receivers The FAR-15s were tight enough to hold the empty mag in the mag well when the mag release button was pushed. In fact, all but the FAR-15 held the 20-rounder noticeably loosely. In contrast, several 30-round mags, from Adventure Line to Radway Green were all "Drop-Free" in all the tested receivers, including the Fulton Armory receivers. So what do you do if you have a mag that won't drop free from your lower? Simple. The area of the magazine that provides the tightness of fit is the "shelf" just below the magazine catch aperture in the side of the magazine. Support the magazine with a two-by-four or equivalent, and smartly rap the "shelf" once. Check the magazine. If the mag still doesn't drop free, repeat. Be sure to check after every "rap" so you don't overdo it. |
Maybe I need more coffee, but the above explanation isn't helping me any. I understand that you are hitting the area below the hole/ catch, but what are you hitting it with? How does this now effect that magazine when used in another AR? 
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| My suggestion would be to buy 2 brand new magazines from a reputable supplier such as DPMS teflon 30s and try them some of the older GI 30s that I have and have seen are a bit spread at the back top of the mag shell. and some Out of spec mags are too long from front to back and they stick. |
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