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WAY TO GO ANDYC!!

First time I have ever heard anyone else propose this happening although I have always thought it possible (weak mag spring allowing top round to dislodge from the mag under recoil) and head towards the chamber via the chamber coming back at it during recoil, then the subsequent round being picked up properly and run into the back of the live round that that left the mag in a way it was not supposed to. I have argued this possibility on double feeds where both rounds are live, but I get a strange dismissive look from all that I have said it to, so I quit saying it several decades ago. I have seen a lot of rounds go down range and of the perhaps 50-75 real double feeds (excluding rim fire) I have seen only 1-2 that were not caused by a failure to extract - for whatever reason. On several occasions I have seen magazines with mess up feed lips allow more that one round out, but on every occasion, it spit the first and sometimes second round straight up and out with the slide catching a round and chambering it (the hard way) during this upward cascade of rounds escaping the bad magazine. I have no statistics to back me up other than my own observations, but I would feel comfortable is saying that 95%+ of double feeds result from a failure to extract. IMHO it is very rarely a magazine issue if the springs are good, and why I no longer dump the "in service" magazine when clearing a double feed. I remove it, store in my strong pinky, turn the gun on its side jack the slide a couple of time (while putting finger pressure on the extractor if it is external) , re-inserting the in-service mag and chambering round. It has always worked. This why a good clean extractor, good extractor tension and a smooth chamber are so important. Double feeds take a precious while to clear even if you are well practice at it. Dang, didn't mean for this to get so long.

Good Beans AndyC

Until the slide has almost fully recoiled, the rounds are not even touching the magazine lips. Once the slide comes fully back, the next round in the magazine pops up and rests against the magzine feed lips for a mere split second before the lower portion of the breech starts pushing it from the rear towards the chamber. Using dummy rounds and an empty auto, insert a magazine and then slight pull back the slide about 2/3rds the length of a unspent cartridge. You will see how the top round of the magazine is actually being pushed down by the lower breech rail. This is why a fully charged magazine is easier to insert in an empty (slide back) reload, than in a tactical reload (slide forward). Once a long time ago, I accidently loaded a 40 cal magazine with 9mm ammo and put in my Glock 19. It never did double feed. Upon firing, 1-2 live rounds would spit straight up through the ejection port and the slide would catch one along the way and chamber it, althouh I suspect it was hopping the extractor over that round and not allowing it to slide up under the extractor as it normally would. This would repeat until the magazine was empty. It was both puzzling and halirous at the time. It took me a few minutes and recharging the magazine twice, to figure out what had happned. I have been proven wrong many times in my life, but at this point, I don't buy that loose lips, etc cause a classic double feed. I am not saying it could never happen, but it is certainly not the first place I would look to especially if changing mags didn't change the malfunction frequency.

TEX

In my experience the vast, vast majority of double feeds are actually the result of a failure to extract. On rare occasions two rounds can try to leave the magazine at the same time, but this usually results in one extra live round being pushed out of the ejection port, or hung up in it, with an accompanying failure to fully chamber. Over 40 plus years of shooting and seeing millions of rounds go down range, I have never seen a double feed that when cleared or inspected, revealed a live round in the chamber with another live round behind trying to chamber. In my humble opinion, the word “Double Feed” should be removed from the gun lexicon and replaced with FTE (failure to extract).

Most often failures to extract are caused by a broken or chipped extractor claw/hook, dirt under the extractor, or a weakened extractor spring. This can be exacerbated by a very rough or dirty chamber. The ammunition casing actually swells or expands a bit when fired and if the chamber wall is very rough to begin with or has collected a significant amount of dirt, it can greatly increase friction, thus increasing the force necessary to extract the round - to the point that the extractor can slip or hop over the case rim, leaving the just fired round still in the chamber. The slide then cycles, picked up a new round and tries to chamber it - resulting in a so called double feed. Occasionally a weak load can result in the slide not coming back far enough for the ejector to pop the round out of the ejection port, but this also usually means it didn’t come back far enough to pick up another round off of the magazine – this is rare.

Check the extractor for damage and clean under it well. Polish the chamber and replace the extractor spring. See if this doesn’t eliminate or greatly reduce the double feeds.