Last barrel I spun on the night before a match. I loaded up some ammo with a charged slightly lower than I used for the previous barrel that would get me near the velocity I wanted. I zeroed it groups looked good, so I chrono'd it put the data in my ballistics app and took 3rd in the match. Ran a bore snake through it when I got home bumped the charge up .2 grains and re-chrono'd /zero'd the next trip. Been killing matches with it ever since.