I've used Kimber mags in my Kimber 1911s (5" and 3 1/2") for about 20 years now and I've found them to be very reliable.
That said, I'm also smart enough to understand how the 1911 functions and feeds and know when not to mess with the engineering.
There are a few things worth knowing before you start blaming the magazine:
1) 1911 magazines come in four basic flavors with four basic feed lip designs that go from fully controlled feed to uncontrolled feed.
- The original magazines had tapered lips (left) and were designed for 200 and 230 gr ball ammunition. The tapered lips give and early but controlled release of the round and they feed smooth as butter in a stock 1911 as the round nose of the bullet starts up the fee ramp a the same time as the rim starts rising into the extractor. However, they don't do as well with hollow point or semi-wadcutter rounds as the truncated cone shape of the bullet tends to jam on the feed ramp.
- after WWI Colt came out with hybrid lip magazines (center) in their commercial Colt 1911s. These magazines have less taper and produce a more gradual release of the rim of the cartridge. They work fine with FMJ ammo, but they also hold the rim down long enough for a truncated cone shaped bullet to start up the feed ramp before the rim is released.
- There are also after market parallel lipped 'wad cutter' magazines (right) that are optimized for the wadcutter bullets that are popular for target shooters and practical pistol shooters. These release the rim of the cartridge very late in the feed process and they do not work well with a 230 gr FMJ as the longer rounded nose on the bullet will often get jammed in the top of the chamber before the rim is released.
- Wilson 47D magazines operate entirely differently. They basically just pop the round out more or less level in front of the slide, which bats it into the chamber, with no controlled feed at all.
2) The different feed lip designs produce different angles as the cartridge feeds and the rim rises up into the extractor. This makes the extractor profile very critical as it has to be profiled to allow for the sharper angles created by the wad cutter style feed lips. If not, the rim can lock as it rises up into the extractor. Some folks incorrectly re-profile the extractor and some folks replace the extractor with an after market extractor that may not be well matched to the magazine feed lips or rounds being used.
3) In the 1911, slide over run and spring weight are both critical to feeding.
Unfortunately, way too many 1911 shooters buy a 1911 and then before ever shooting it go on line and start asking what 'upgrades' it needs. They end up replacing the recoil spring, usually with one that is heavier than the factory spring. This can reduce the slide over run, and it will also increase the slide velocity, which screws with the timing of the feed cycle.
Way too many shooters also install a shock buffer to reduce the potential for frame battering. They work ok in 5" 1911s as there is enough excess slide over run to usually avoid feed issues - provided the shooter also did not install an extra power recoil spring. However in the shorter Commander length and Officer Model length 1911s the slide over run distance has been reduced to the point that adding a shock buffer will reduce the slide over run to often insufficient levels.
4) Finally, there are shooters who don't understand that springs wear out. Too light a spring can cause the frame to rebound off the frame with the result that you get more slide velocity moving forward as well as backward and you end up with insufficient over run time to allow the round to feed properly.
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Kimber uses Colt Commercial hybrid style magazines and they feed well with just about everything, provided the shooter allows for a couple hundred rounds to allow these fairly tightly fitted pistols to break in, and don't mess with the springs, extractors or install things like shock buffers. That break in period, when fired with standard pressure ammo, will also help you learn what the recoil should feel like, and 800-1200 round out, when the recoil spring wears out, you'll notice a more 'metallic' feel to the recoil that is your sign to replace the spring - if you let it go that long in the first place.