I have a left hand .22-250 RAR with the 1 in 10 twist.

My solution was to clamp the muzzle in a stationary vise then put a barrel wrench on the breech end. Two turns counter-clockwise and voila, a 1 in 8 twist! As a plus, you get some nice faux flutes in the barrel...


Gunnery, gunnery, gunnery.
Hit the target, all else is twaddle!