My favorite load in a Garand or my target 30-06 is 168 Match, 47.0 grains IMR 4895 any case, CCI #34/WLR
This load is appropriate for Garands, but is "a not to exceed" load in Garands.
Cutting by a grain won't hurt anything.
I have this two groove barreled M1903A3. This load shot very well in that rifle, but the rifle has a “slow barrel”. Data below. If you have a slow barrel that does not mean pressures are also low. In match barrels this load is closer to 2650- 2700 fps.
I have shot in competition, standing and sitting rapid fire 200 yards, 168 Match 42.0 grains IMR 4895. In a match bolt rifle it shot cleans on a seven inch 200 yard ten ring. Obviously this is a mild load. However, service rifles seldom shoot well with ammunition that is too far from service ammunition pressures and velocities. So, I don’t know how it would do in a M1903.
Let me recommend 47.0 or 47.5 grains IMR 4895 with a 150. This just duplicates pre WWII service rifle velocities, is mild, and accurate.
OAL is always LT 3.30”. These bullets are not jump sensitive, so load for function.
A GI barrel, if you get ten shot groups around two inches, that is good. It is really good. GI barrels are not target barrels. You want a round group. If your group is not round, maybe your bedding is shot.
I picked up a M1917 at CMP North this July. This rifle shoots 14-12 inches high at 100 yards. I really don't know, I never got a good aimpoint. It needs to be bedded and needs a new taller front sight.
Stuff like that happens with these old rifles.
M1903A3 two groove barrel
168 Nosler 47.0 grs IMR 4895 W/W cases WLR (brass finish)primers
22 Dec 01 T = 54 ° F
Ave Vel = 2514
Std Dev = 29
ES = 101
Low = 2456
High = 2557
N = 15
M1 Garand Rack Grade
150 gr Sierra Match HPBT 47.5 IMR 4895 CCI#34 WWII cases OAL 3.30"
24 Mar 04 T= 70 ° F
Ave Vel = 2630
Std Dev = 33
ES = 109
Low = 2580
High = 2689
N = 16