Out of boredom, I dug my old Remington 597 out of the dust bin (my first rifle, purchased on my 18th birthday). I cleaned the hell out of the barrel, polished the muzzle, free floated the barrel, gave it a fresh camo paint job. Then I opened her up and polished the hell out of the internals, slapped a rail on her and put a scope on.
I bought 5 different types of ammo and shot them all for comparison. I've found that the higher the velocity, the more the accuracy varies. Remington subsonic rounds, I can consistently hit the Bear on a tin of mint grizzly at 50 yards... Yet somehow can't hit ONE damn crow I shoot at