My 358 is cut at 20". With the shorter bullets I am happy so far, but as I said I have yet to make a kill, so the jury is still out. Accuracy has been just fine.
220 grain bullets clock at 2428 FPS for a 5 shot average. 180 grain bullets gave me 2698 FPS average. I had some 200 grain round noses that shot even better then the 220s, but I never chronographed them so I can't say what speed they averaged. I hope to get a crack at some deer and antelope and maybe an elk or 2 in the next season.
The 20" is what I was originally thinking of. I priced out having one built but McGowan and I didn't think it's too bad. I'm glad you said something about the twist rate, I was just about to order a barrel from Wilson combat just because they have a good sale, but it's 1:14 twist. I'm going to use it for black bear here in Michigan, so I want it to be able to accurately shoot heavier bullets
