Good mag. just won't work in my application - ProMag Glock 21/30 .45 ACP 22 Round Pistol Magazine

I have a New Frontier C-45 carbine. A factory Glock magazine has a very tight fit. The ProMag doesn't hold the ammo high enough to pass the straight wall design of the chamber. Even 1mm can make the difference. I need Glock magazines with closer tolerances to function.