The 1911, Finicky Magazines, Finicky Ammo, And You
So, I had a bunch of 10-round magazines for my 1911 from Metalform. They're pretty much the only company who makes them in .40 S&W, even Springfield Armory sells them under their brand name. Well, I originally thought they were all bad, since they constantly misfed the ammo I put into it. To a certain extent it was true, as the feed lips prevented the cartridge from being pushed up easily into the chamber. I stretched the feed lips out just a little with a .410"-diameter steel rod and I noticed that some worked better, and some still did badly. When I took a further look, I noticed what was happening with the ammunition that didn't feed properly. It was actually setting the bullet back into the cartridge. So, I investigated the ammunition further, and compared brands. The Blazer Brass .40 that I was using was constantly being pushed back into the cartridge and jamming, regardless of which 10-round magazine I used. Blazer Brass works fine in all my 8-round magazines, probably due to the slightly different feed lip configuration. The Metalform 10-round magazines don't let the cartridge push up the ramp as quickly as the 8-round magazines do. The feed lip configuration combined with Blazer Brass having a very loose crimp on it is what led to my problems with the 10-round magazines. The Winchester White Box that I got a few weeks ago doesn't have that problem, as it fed well in every magazine but three. I'm going to try again with those three bad magazines just to make sure they're actually bad and it's not just the ammunition.
I won't count on those 10-round magazines as anything but plinkers and the occasional Limited-10 match, but it's nice to know that when I need practice magazines, I've got some that I can use for just that purpose.