Chip McCormick Power Mags.

[Tcruse]

If you have problems you can purchase Wilson Combat followers and springs for about $4 per set and will fix most issues. I had a few stainless mags marked with "colt 45" on the bottom that were always not reliable until switching out the followers, now 100%

 

[Shootshellz]

Since no one has mentioned Mec-Gar 1911 magazines, I will (since I like them a lot).