Check out the 1911 forum. There’s a whole section over there devoted to magazines. Personally, Ed Brown works well for me, and youcan’t go wrong with MecGar. Stick with 7 rounders, as God and John Browning intended.
A lot has to do with how much you want to spend. Personally I have not had bad experiences with 8 round mags but I have read some detailed articles that if they don't extend just a little past the end of a full size grip frame they are not a good 8 round design. I rarely hear good things about ProMag. The premium brands of Wilson and Ed Brown are everything you would expect. MecGar makes factory mags for many gun companies and can be trusted for just about anything. For my 1911's I have a lot of Metalform and Shooting Star by CMC. I have had success with most all designs in some mags: flat followers, round followers, plastic followers. Just one guy's opinion from my experience.
Genuine factory Colt mags are excellent and highly recommended. They contract with companies like Checkmate , Metalform or Okay Industries. 7 rounders tend to be the "most" reliable but I have had 100% reliability with Colt 8 rounders in my Colt made 1911s.
Make sure you deal with a reputable dealer like Brownells or Midway to make sure you are getting real Colt mags. Do not buy the gun show mags that say "Colt 45" on the bottom they are junk.
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