In all sincerity, since we trashed Pete's thread here... this comes down to what I always stated. If you have an accurate gun - then it's always accurate. Barrel length doesn't matter, if it's a shorter barreled gun - it's accurate. After that, you just need to know the ballistics on the load, and the muzzle velocity out of that barrel - so you can make the right drop-at-distance choices. Accurate guns are always gonna be accurate, but if you wanna take something short-barreled to a longer distance, the only things stopping you are the limitations of the load, and whether you know your dope for that distance...
I've done 12.5" Grendel at 850 yards, never tried to push it beyond that. That load goes subsonic at right after 900, and before 950... I'm about to get into some 12.5" 6 ARC at that same distance, and longer - as long as I can make it go...