Just bought a TRG-42 chambered in 338 LM and decided to try out the OCW method for working up a load. I tried it once before with a .308 rifle but didn't get better results than my other approach, which was to load up a whole bunch of rounds and shoot a whole bunch of 5 & 10 shot groups.
Anyway,
- new Lapua brass
- Federal 215M primers
- Retumbo powder, 92 - 98 grains in 1 gr increments (3 each)
- 250 gr Lapua scenar bullets
Cases were neck sized only with a Redding 365 bushing. All cases were 2.720" in length. Bullets were seated to an OAL of 3.612".
Shot 3 of each charge weight in round robin fashion at 200 y after zeroing with some factory ammo.
Velocity data -
POI data (eg, the 93 gr 3-shot group averaged .24" right and .05" high of my point of aim) -
The velocity curve flattens a bit at around 96 grains, and there's an average POI cluster in the 95-96-97 area, so it looks like 96 grains or thereabouts is the sweet spot for this rifle.
The first groups were OK, nothing spectacular but as I understand it the OCW method instructs us to not get hung up on absolute group size at this point. 1.2" @ 95 gr, 2.3" @ 96 gr, and 2.1" @ 97 gr (at 200y, so right around MOA).
A few questions
1) Any comments or suggestions, I'm new at this.
2) Should I next try adjusting seating depth, or vary the charge weight around 96 in smaller increments?
3) Any point in changing the neck size bushing to mess with neck tension?
4) The suppressor is sitting at my dealer, waiting on the ATF. Will I need to start the load workup over at square one after I pick up the can and start using it?
Thank you.
Anyway,
- new Lapua brass
- Federal 215M primers
- Retumbo powder, 92 - 98 grains in 1 gr increments (3 each)
- 250 gr Lapua scenar bullets
Cases were neck sized only with a Redding 365 bushing. All cases were 2.720" in length. Bullets were seated to an OAL of 3.612".
Shot 3 of each charge weight in round robin fashion at 200 y after zeroing with some factory ammo.
Velocity data -
POI data (eg, the 93 gr 3-shot group averaged .24" right and .05" high of my point of aim) -
The velocity curve flattens a bit at around 96 grains, and there's an average POI cluster in the 95-96-97 area, so it looks like 96 grains or thereabouts is the sweet spot for this rifle.
The first groups were OK, nothing spectacular but as I understand it the OCW method instructs us to not get hung up on absolute group size at this point. 1.2" @ 95 gr, 2.3" @ 96 gr, and 2.1" @ 97 gr (at 200y, so right around MOA).
A few questions
1) Any comments or suggestions, I'm new at this.
2) Should I next try adjusting seating depth, or vary the charge weight around 96 in smaller increments?
3) Any point in changing the neck size bushing to mess with neck tension?
4) The suppressor is sitting at my dealer, waiting on the ATF. Will I need to start the load workup over at square one after I pick up the can and start using it?
Thank you.
