I have finalized two loads for next years hunting season for my 300Win mag and my 358Win. I am using a 180gr TTSX for my 300Win and the 225gr Accubond for my 358Win. Results of my tests were as follows.
For the 300Win mag I used the following powders with Win Brass and CCI250 primers and with all powders listed the largest group with my 116FHSS Savage was 1.285" and the smallest group was .454"
RL-25 = 3051fps (fifth most accurate group .887")
RL-22 = 3099fps (fourth most accurate group .856")
RL-H1000 = 2968fps (worst group 1.285")
MRP-2 = 3025fps (third most accurate group .768")
MRP = 3129fps (second most accurate group .6789")
IMR4350 = 3052fps (sixth most accurate group .977")
H4350 = 3002fps (seventh most accurate group .989")
W-760 = 3074fps (most accurate group .454")
Most accurate group and load with 180gr TTSX 300Win Mag, W-760, 3074fps, .454"
For the 358Win, I used one load of TAC but two different primers Fed 215 and CCI250, with CCI250 primers giving more velocity and best accuracy.
Tac = 2552fps with Fed 215 primers
Tac = 2587fps with CCI250 primers and best group of .528"
Most accurate group and load with 225gr Accubond 358Win, TAC, 2587fps .528"
No pressure signs at all and very easy ejection.