And now back to your regularly scheduled programming of load development....
GA Precision PPR rifle 6gt 260 rounds fired. I have been working loads with several powders, primers, and bullets. Here are best results in my rifle. Please note only testing combustion, not tuning. Seating depth with group analysis will be next. Here I focused on speed, ES, and SD.
112MB, alpha brass, Cci450, Coal 2.540, Rl16
36.8 2885fps 13Es 6Sd 5rds fired
37.0 2884fps 5Es 2Sd 5rds
37.2 2910fps 6Es 2Sd 5rds
37.4 2919fps 9Es 3Sd 4rds
105Berger Hy, horn brass, S&B primer, Coal 2.560, IMR4166
34.0 2979fps 21Es 8Sd 5rds
34.5 3018fps 17Es 7Sd 5rds *no obvious signs of pressure*
--same as above but Cci450 primers--
33.5 2942fps 11Es 4Sd 5rds
34.0 2972fps 26Es 9Sd 5rds
105 hornady Bthp match, horn brass, S&B primers, Coal 2.500, IMR4166
32.4 2865fps 6Es 3Sd 5rds
*group was one hole .3 or less
All brass was on second firing and first resizing. Shoulder bumped .002 with RCBS FL .266neck bushing. Trim 1.720.