Don't clean it anymore.
Seat the bullet even with the lands (as long as it still fits in the mag) , start at 41.5 gr of H-4350 and work up in .3 increments to 43.0 gr. It'll shoot somewhere around 42.0 but check them all. Once you find the powder charge thay does the best THEN play with jumping the bullet. A-maxes are not known to be sensitive to the jump but you can test it if you like. Testing all this 200 yards to 500 yards will tell you more. Testig at 100 may have you measuring groups in thousandths instead of 1/16" or 1/8". For really good barrels 300 yards can be hard to read. 500 is better provided you don't have a ton of wind.
Oh and a routienly shooting 1/2" rifle is not a problem at all. In fact that's really good, and "single holes" are not super common.
Thanks, I am going do that this week.
To be honest, it's probably me shooting poorly and not the rifle or the round!