Take your pick, I settled for 4227 at 10.0 for now. I think 4227 sounds better than 1680 and is a bit cleaner burning. No FPS numbers since my chrono somehow acquired a hole through it.
As always what's safe in my gun may not be safe in yours. YMMV
208 Hornady AMAX with IMR 4227 @ 10.0 grains
Need to chrono but appears subsonic
Cycled & locked bolt open with CAR stock and Enidine buffer.
208 Hornady AMAX with 1680 @ 10.1 grains
Need to chrono but appears subsonic
Cycled & locked bolt open with full size A2 stock and standard rifle buffer.
208 Hornady Amax with 1680 @ 10.3 grains
936, 977, 995 FPS = 969 average
Cycled with heavy 9mm buffer in CAR stocked lower.
208 Hornady Amax with 1680 @ 10.5 grains
Only checked 2 rds - 1006 & 1061 FPS, these were loaded shorter than the rest
Cycled with heavy 9mm buffer in CAR stocked lower.
225 Hornady Match with VV N110 @ 8.5 grains
1071, 1051, 1045, 1067 FPS = 1058 average
Cycled but did not lock bolt with heavy 9mm buffer in CAR stocked lower.
225 Hornady Match with 1680 @ 10.0 grains
966, 927, 973, 993, 940, 942 FPS = 956 average
Cycled with heavy 9mm buffer in CAR stocked lower.
225 Hornady Match with 1680 @ 10.1 grains
Need to chrono but appears subsonic
Cycled & locked bolt open with full size A2 stock and standard rifle buffer.
225 Hornady Match with 1680 @ 10.3 grains (Remington cases)
FPS = 973, 976, 986 (75? temp)
FPS = 938, 945, 981 - these were crimped with the Lee FCD.
Cycled & locked bolt open with full size A2 stock and standard rifle buffer.
225 Hornady Match with 1680 @ 10.5 grains (Remington cases)
FPS from 1056 to 1076 FPS
240 Sierra Match King with 1680 @ 10.1 grains
Need to chrono but appears subsonic
Cycled & locked bolt open with full size A2 stock and standard rifle buffer.