I have a friend who is having severe trouble getting his 45 cal CVA to group at all. I tried to explain about the bullet weight/powder charge vs the rate of twist in a particular barrel but had a brain fart and for the life of me cant remember the rule of thumb to start from. his rate is 1 in 28, 100 grain cleanshot with a 245 gr powerbelt copper clad HP, he also has 190 gr bullets to experiment with but I told him to pick a starting point and get that working first. Can anyone "refresh" this burnt out brain here.

10 Pointers