I use CCI450's & CCI 41's in SRP 6CM & 6.5 CM with extruded powders like H4350.
For ball powders I like Rem 7 1/2's
This attachment might be of interest -
Table 1 gives info - Rem 7 1/2's are real sparky - don't let stuff like kPA (kilo Pascals- unit of pressure - Pascal is 1 newton per 1 square meter) deter you from reading this. Newton is force needed to accelerate/move 1 kg mass 1 meter per second per second
My 6.5CM & 6CM run on a steady diet of Staball 6.5 & Rem 7 1/2's. The 6.5CM with max loads of R-S Hunter & 120's at 3,000 fps, approaches the famous .270 Win for practical results, like dead deers. Dependable results at temps under 30 F.
6.5 CM ammo having CCI 41's & RS Hunter exhibited wide swings of velocity and printed double groups at 300, like two 4-7 shot groups 4-5 inches apart at 300. Not to be used, especially in cold temps.
Extruded powders are no longer made in the USA - read about horrific explosions that devastated multi acres & busted windows 1/2 mile away when 10 or more tons of powder ignited during drying stage (solvents). WWI - machine gun & other stuff use - death & destruction ending with Spanish flu taking 1/2 mil more lives worldwide. A visit to the abandoned, sad, & desolate Belmont town cemetery in Montana has many graves of Spanish flu victims. One grave marks the life of a USN sailor who was "lost at sea" during the WWII battle of Okinawa. My grandparents were immigrants from France and served a strong woman who volunteered as a WWI battle field nurse then cared for Spanish flu patents, as a little kid I got to hear about this stuff - entire villages wiped out by artillery fire, then chem agents.
Only ball powders are made in the USA - part of the manufacturing process is done underwater. Rifle ball powders have heavy deterrent coatings and need sparky primers like the Rem 7 1/2 (2303 kPA). Very fyne accuracy might be obtained with CCI450's & H4350 (Australia)