Load Development Help... Again... 300wsm with 215 hybrids

[Winston]

G'day Folks,

Was out playing with my new 300wsm on Saturday (215gr hybrids, moly, 29.25" barrel on a Bat M). Had 5 loads to test, 0.4gr apart. The original plan was to shoot some 140 yard groups, but the club shoot was at 600 and they left a frame up for me. Conditions were great, so I thought I would shoot them at 600 instead and look at the vertical I was getting.

Procedure was as follows. Shoot 5 shots of the same load in quick succession, pack up rifle, drive to butts, pull target, circle shots from that load, raise target, drive to mound and repeat with the next load. Because they were all shot on the one target, I ended up with a ladder test of sorts, which I thought could provide some insights. While I thought the drive to the butts and back would be enough of a wait between 5 shots to cool, this wasn't the case and by the 5th group a did have some barrel mirage to contend with, so results may be skewed a bit.

Does anyone have any wisdom to share looking at my target? 60.0 has a shade over 2 inches of vertical and overlaps three shots from 60.4, so I am thinking that a whisker over 60.0 (maybe 60.2) is the place to be.

Interesting that 61.2 had three shots touch and then two well outside that. Also interesting that 61.2 printed lower that 60.8. I have no explanation for the high shot 60.8 threw other than inconsistent shoulder pressure. Im still learning how to best control the recoil.

As usual any and all feedback is greatly welcomed. I might do the test again this weekend starting hot and coming down to see the effect of barrel heating, or maybe 10 shot groups of 60.0, 60.4 and 60.8.

What do you all think? Should I just take 2 inches of vertical at 600 (60.0gr) and start shooting?

[RDavies]

I think your method was spot on, from the plot it looks like 60.0 would be the group as it has least vertical, but also because the other groups cluster around it. The hotter loads with the one off high shots are a sign of being at the top of the node. I would say it was likely the 2 high shots on the 2 hotter loads would likely have been the first shot fired after you got back when you combine a cold dirty bore shot (usually slightly higher velocity), combined with being at the top of, or slightly past your node.
How about next time you go to a club shoot, you do 10 shots each of 60.0 and 60.4 and see how the plot looks.
Once you have seen which is best out of 60.0 and 60.4, then maybe try different seating depths. before fine tuning powder load again at a later date.

[Winston]

G'day Rod,

You're spot on about the high shots, they were indeed the first shots out of the hottest three loads (I was able to spot them through the scope).

Without ET's, looking at the group shot during a club shoot is a bit difficult - I'll have to talk the fellas into letting me use two new centres!

We're shooting 800 this weekend, I'll try the two charges you suggested and report back.. If the blokes won't give me new centres, I'll just stay back and shoot a couple of groups when the sun gets low

Cheerio

[Paul Janzso]

Hi Winston
I shot the 300WSM for many years and had favourite 2 loads for it.
My longer range load was 60.gn 2209 with a 210gn VLD Berger 15 thou jam and my shorter range load was 190gn VLD Berger with 62.5gn 2209 and same jam.
These loads had the same 300 meter or yard zero so I could start with either load depending on conditions.
I tried the hybrids but to me there are so many variables with seating depth that I just stuck with VLD's
My original barrel after rechambering and ending up at 28 inches still shot a 3 inch, 10 shot group at Belmont 1,000yard BR with the 210 VLD load
Cheers
Paul