Re: 260 sub sonic
If it's stable out of the muzzle, it's going to be fine out to as far as you can hit with it. The round will have a rainbow trajectory, but as long as you have elevation and wind adjustment left, you can keep going.
I wouldn't use it for hunting beyond vermin control, but if you feel you can cleanly kill an animal with a 22 or 22mag, then this will do the trick.