Daniel,
I am not sure on the C.O.L.
The groups with RL 15 were the best out of all the powders I tested, about .5 inch. But my gun does not really like the 55gr. bullets as it is a 16 twist and is seen best with the lighter bullets. I use RL 15 for 50gr bullets also. I am not sure what kind of game you are after (PD's, Paper, or deer) but the most accurate 55gr. bullet I have shot is the 55grFMJ sierra and I shoot everthing with it, plus they are cheep, often <$10 a box. I also experience less fouling with this bullet. Just a thought.
[ 04-28-2003: Message edited by: MTBA ]