More Load Development Questions

[mmattockx]

Got out with my new .338 Win Mag yesterday (early 80's Ruger 77). Sighted in with commercial ammo, then shot two strings of 10 rounds each, looking for upper load limits and pressure signs. Both strings used 225gr. SST's, with one using IMR-4831 powder and the other RL-22 powder. I simply fired all 10 at one target, mostly just watching for pressure signs and getting used to the recoil. Range is 100yds. I wasn't trying for groups or anything, but the results were interesting enough that I thought I would ask for opinions on what I see here.

RL-22 target:

Note that the shots are pretty uniformly scattered. I started at 69.0gr and worked up to 75.0gr.


The 4831 target:

The shots are not all scattered in this one. This one started at 69.0gr and worked up to 74.0gr. The first 3 (light) loads threw 3 of the 4 fliers, the bottom left one and the two top right ones. The final (maximum) load threw the far right flier. The other 6 went into that tight cluster that is well under an inch. The loads were incremented in 0.5gr steps for the upper part of the charge weight range.

To me, this indicates a pretty wide node right in the upper portion of my load range and that 4831 is the better choice to pursue for load development. Would that be correct?

Note the rifle is for hunting and is bone stock, not bedded and the barrel is not free floating at all, with a number of contact points along the forearm. Groups did not seem to open up with the heat of firing 5 round strings, which was a nice bonus, considering the lack of tuning that has been done and the forearm contact.

Any thoughts on where to go from here? I am thinking a test with 0.3gr charge increments through the weight range that gave the 6 round cluster with the 4831 and using 3 round groups at 200yds.

Thanks,
Mark

 

[Mystic Precision]

You will likely find a good load with the 4831 before the Reloader but that is not to say the Re will not work.

I would definitely free float the barrel and bed it. At least free float the barrel so this doesn't create any uncertainties.

Beyond that, you are heading in the right direction. As a hunting rifle, I would suggest no more then 3rds at each powder increment letting the barrel cool right down before shooting the next group.

when you find a couple of good loads, retest with a few more 3rds groups at each level then use the one with the most consistent accuracy.

For me, the most accurate load AND the one with the best cold bore shot is what I will choose. There is little point in testing a hunting rifle with a hot barrel, this is unlikely how you will hunt.

Enjoy...

Jerry

 

[X-fan]

RL-22 is a poor choice for that application...School of hard knocks bro.
RL-19 is the cat's jammys for that bullet and chamber.
It helps to notate each bullet hole.

Good info from Jerry.

 

[mmattockx]

RL-22 is a poor choice for that application...School of hard knocks bro.
RL-19 is the cat's jammys for that bullet and chamber.
It helps to notate each bullet hole.

Good info from Jerry.

I will be trying the RL-22 with 250gr bullets, I had it on hand so I thought I would give it a shot with the 225's. I am planning on trying RL-19 with the 225's, but haven't got around to picking some up yet.

Mark