338 LM load development?

[7.62_Reaper]

i have been having trouble tweaking my cartridge to be able to achieve 1/2 moa or better in my 338LM. i did my ladder test and it showed that the high node is between 89.5 through 90.5 gr of Retumbo. i started shooting groupings (4 groupings, 5 shots each with the same load for a total of 20 rounds, i did this for three different recipies) and i have been getting the same bad results, i can't seem to find the right formula for this rifle.

any thoughts of what i can do different or what I'm doing wrong thanks

 

[7.62_Reaper]

the load i used for this set of groupings was 90.5 gr of Retumbo lapua brass and lapua 300 gr sencers set at .01 off the lands

also ignore the center target that isn't one of the groupings

 

[webcruzzer]

What's wrong with the lower left group???

 

[Dogtown]

I would use the powder charge from the lower left group and load up some more with different seating depths to see how they group.

 

[ChrisGarrett]

Not all barrels, ammo or shooters are able to consistently shoot 1/2 MOA 5 shot groups.

Just sayin'.

Chris

 

[7.62_Reaper]

What's wrong with the lower left group???

all the groups were using the same load (90.5 gr retumbo) so my groups are inconsistent

 

[7.62_Reaper]

Not all barrels, ammo or shooters are able to consistently shoot 1/2 MOA 5 shot groups.

Just sayin'.

Chris

i have no issues getting 1/2 moa 5 round groups with my 308, which is why this is getting frustrating

 

[ChrisGarrett]

i have no issues getting 1/2 moa 5 round groups with my 308, which is why this is getting frustrating

Maybe, maybe not. I don't know you, but my point is that it's not a super common thing to be able to shoot seven, or eight out of ten, 5 shot groups with any particular weapon, ammo or shooter. It's hard to do consistently and some barrels/ammo/shooters just aren't up to the task.

Getting one, or two, sure...even a blind squirrel finds an acorn from time to time, but that's the exception and not the rule.

People seem to take it for granted, that everything out there should be shooting 1/2 MOA, or better, for almost every group fired.

Chris

 

[zackm]

I have not tried the lapau bullets. But i have found in my rifle and several other 338 lm rifles the ocw for a 300 gr bullets seems to be at 89.3 gr of retumbo. Now i have only used 300 gr otm bergers and 300 gr smk. But they work really well.

What type of 338 lapua are you shooting (gun maker)?

 

[L8fr82hub]

Is your scope tightened down properly? I've experienced inconsistent results like that twice and both times the scope was the culprit.

 

[AIAW]

Did you chronograph any of these or just going by the group printing?

 

[wvlapua]

Didn't mention the twist rate. Your barrel may be having a hard time stabilizing the 300g bullets.

 

[NICETRY]

You say you have no problem with your 308 but you do with your .338 Lapua. It could be you. Have you tried shooting it with a dummy round to see if you flinch a little?

 

[7.62_Reaper]

I have not tried the lapau bullets. But i have found in my rifle and several other 338 lm rifles the ocw for a 300 gr bullets seems to be at 89.3 gr of retumbo. Now i have only used 300 gr otm bergers and 300 gr smk. But they work really well.

What type of 338 lapua are you shooting (gun maker)?

custom build by Dave Viers (Viers Co.)

 

[7.62_Reaper]

Is your scope tightened down properly? I've experienced inconsistent results like that twice and both times the scope was the culprit.

torqued to NF specs

 

[7.62_Reaper]

Did you chronograph any of these or just going by the group printing?

just printing

 

[7.62_Reaper]

rifle specs:
stiller tac 338 action
28 inch benchmark barrel with a 1:9.5 twist
jewell trigger set at 1#
set in a manners T5A stock

 

[jkonzal]

My experience is that bigger bullets like a lot more jump. I run my 300gr SMK's with .035 jump.

 

[mdmp5]

i have no issues getting 1/2 moa 5 round groups with my 308, which is why this is getting frustrating

Did you try playing with your jump? Give that a try in .01 increments.

 

[outlaws51]

I had to seat the 300 otm's on the lands to get a consistent grouping when playing around at 100yds. Have you tried RL33. I know Retumbo works but you might be surprised with the results with a different powder. I did. I also noticed at 1000yds the rifle preformed way better than I thought. Hitting the target is what matters.

 

[Maelstrom]

I have had good results with 86.5 gr of Retumbo loaded to 3.612 with 300 Lapua Scenars. My groups really start to open up as I get past 87.5 or 88 gr of powder.