So to start, Glock has a 60% market share in the US domestic pistol market.. They are great pistols, well made, dependable and great to shoot. So if I want a carbine in pistol caliber, why would I want to deal with the stamped Colt-Uzi mag from the competitors? The Glock mag rocks, and is completely compatiple with our carbines. Our lowers are machined from the start to take the Glock mag- never a block insert.