multiple caliber

I have been looking at pistol caliber carbines for quite a while now and have received some recommendations, but now I am looking at Olympic Arms for a 10mm carbine. They can also supply uppers for 9mm and .45acp. The magazines are proprietary and are pricey at about $45.00 a copy. This would...

When putting together a long slide build I have wondered what is involved and what is compatible on putting together a pistol that can be used as a platform for multiple calibers? Of course barrels, recoil springs, magazines would need to be changed. Anybody out there who has done this type of...