Let me start by saying I'm a CP fan. I really like the fact that CP allows you to buy their barrels in 3 different bore sizes. The Proto is a .690, and my CP is a .689. I compared the 2 side by side. The Proto I have is a 12" and my CP is a 14". They were both just as accurate as the other. The only thing I found different is the CP shot about 7 FPS faster than the proto. I have my own chronograph. I'm guessing the extra porting the Proto has over the CP, plus the CP is 14" made the difference. The Proto is lighter than the CP, but looks better IMO, and is a tad more quiet due to more porting.
As good as a CP, so that makes it one of the best single bore/non kit barrels that is made.