I have 4 of the Brownell's 10 round mags that I haven't had any issues with and I didn't have any problem seating a full mag on a forward slide. They are what I carry with the Colt. Also for what its worth, I haven't had any issue with the 6, 9 round Colt mags or the 2 CMC mags I have. The gun is a Colt Commander with a little over 3000 rounds through it.