Okay, kind of a repeated question on here because I have seen so many people talk about it. I know some Glock models can fire multiple calibers. In order to do this, what model Glock do you need and what parts need to be upgraded/changed? I have also heard you can do the same with the Sig P226. What needs to be changed in both handguns to accomplish this? Are barrels interchangable? Or can you shoot multiple calibers with an upgraded barrel? Any help would be greatly appreciated!