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Posted: 6/19/2016 11:49:31 AM EDT
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Having an issue with my recently completed pistol build. P mags insert into and can be removed from the magwell fine. Ditto with Israeli steel mags. Many GI mags though are hard to lock in. Some won't lock in at all and some that require a good thump on the bottom to lock are nearly impossible to remove. All the mags work in my CMMG. The pistol is built on a SWAT Firearms billet lower. There is some scuffing inside the magwell and on the recalcitrant mags. Is this just normal manufacturing variation in the mags or is the magwell tight or out of spec? Best case is for all my mags to work on both my AR's. Ideas, opinions please.
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Have you tried inserting them with the bolt locked open. Spring pressure against the bullets pushing on the bottom of the BCG causes some magazines to be hard to insert.
I've never heard of SWAT billet lowers so I can't speak to their build quality. All machining operations have tolerances and your seems to be on the tight side. You could dedicate the magazines that work to that pistol and use the GI mags in another rifle. |
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What brand USGI mags?
When you look up into the mag wells inside front surfaces, is the upper receiver lip hanging over the top of that surface, or are the two surfaces flush instead. What mag release button and if a standard release button, is the tip of the mag catch assembly threaded section flush with the face of the mag release button? Also, did you lube the mag catch assembly parts when they where being installed, and you have no biding when you are pushing the button in with no mag in the well. Lastly, if the mags are really USGI manufacturer mags (and not some clone knock off), strip a mag completely down to just it body, remove the mag catch assembly from the rifle, then with the bolt locked home, stick the mag body into the mag well all the way until the top of the feed ramps bottom out of the bottom of the carrier, then look at the mag catch side slot on the non ejection side of the rifle and confirm that the mag's cut out catch slot is at least to the bottom of the mag catch assembly bottom shelf. And no, stripping a mag down for this test is not out of line, since you should be stripping all your brand new mags down to given them a good CLP cleaning before they are used (you do it with a new rifle before it shot, and should be doing it with new mags as well). Hence some mags are assembled in less than perfect condition, and this removes any debris that may have gotten into the mag during assembly. To add, when you are loading a mag, the mag is correctly loaded with the max amount of rounds when the top round in the stack can be pushed down about 3/4 of the way as if it was going to accept one more round. Hence, just because the mag body may be a 30 round type, some of the new anti tilt type follower will take up a rounds worth of the space in the mag (making a 30 round mag a 29 round mag instead. Simply, on a fully loaded mag when loaded against a locked home bolt, there has to be the needed space for the round stack to be move down at least a 1/2 of round space down in the mag as the stack it being shoved up against the bottom of the carrier when the mag is locked home on the mag catch. And yes it is normal to have to palm slap a new correctly loaded mag to seat it home. As stated, the round in the mag are being driving down in the mag via the bottom of the carrier as it locking home, and with a new mag spring that has not taken a set yet, some may be harder than the others to seat home via the palm slap to the bottom of the mag. |
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