My shortest specialty pistols are 14 and 15 inches. I have used them at the MOA BR match: 5-shot group shooting at 500, 750, and 1000 yards.
I have shot 5 shot groups that are 1/2 MOA out to 1000 yards with them.
One was MOA Maximum in 6.5-284, and the other is a XP-100 in 6mm Long Dasher.
The Long Dasher has grouped well out to 1400 yards, but I haven't tried further than that.
It will easily shoot further than that though.
My 6 XC HSP has a 15" barrel and was putting them close together (beautiful conditions) at 1280 yards the other day at a mountain shooting school.