I chronied CCI standard velocity ammo once, shot out from my target pistol with 5"-ish barrel. Velocities were very consistent around 920 fps. That is some 150 fps below advertised 1070 fps. As to accuracy - that same pistol deliver rifle-like accuracy when benched, and I have a feeling that given the same sight radius it will be just as accurate as target rifle.
Longer barrels may still give better percieved accuracy because of weight of the barrel distributed far out and thus dumping adverse movements induced by the shooter.