alexander80,
Welcome to the forum and yes you have a great gun. You have obviously become very comfortable with the gun and it shows in your shooting skills. The GP-100 is one of the finest revolvers you could own. They are built like a tank and can handle just about anything you can stuff in...
I carry my 2 1/16" DAO SP-101 in the same holster as my 3 1/16" SP. It fits fine and is very comfortable. Since most of the holding is done with the frame, cylinder and trigger guard, barrel lenght has little or no affect on the stability in the holster. Here is my Don Hume 721 OT, bought brand...