Choosing powder...

[wind gypsy]

H1000 was the primary powder I used with 6.5 SAUM. Case fill was never a problem. WSM case is bigger than the SAUM case so by deductive reasoning case fill will not be a problem. It seems Gordon's Mental Masturbation Tool is leading you astray.

H1000 and N565 seem to be the available temp stable powders for such cartridges but I bet N570 would look better than either from a velocity standpoint. 6.5 WSM is an overbore SOB and n570 would not be too slow burning.

Edit to add more: H1000 has been a good performing powder for me with heavies in 7 SAUM which is even less overbore and thus case fill would be even tighter. H1000, N565, N570, Retumbo is the burn rate range and powders I'd be looking at.

 

[TaperPin]

I am pretty sure that 100% case fill equates to the powder coming right up to the shoulder neck junction.
Drop tubes help considerably to eliminate the need for tapping as well. Just an FYI.

I’ve never liked drop tubes, but have tried them at all different lengths from 12” down to 2” - always seemed to get better compaction by tapping the case. I’ve loaded a few thousand heavily compressed loads and have always looked out for anything to make it easier/faster. The best 338 loads with Reloader powders are almost always heavily compressed - hopefully we see Reloader powder again.

The technical fill amount as I understand it is the entire free case volume with a bullet seated to the stated col. Fairly simple to determine by weighing an empty case and bullet. The case has a small hole at the neck/shoulder junction to let water out. Case is filled with water, bullet seated and weighed again. The weight of water is converted to a cubic volume, and powder manufacturers provide bulk powder density so multiplying the two is a theoretical weight at 100% fill - the actual % is then adjusted based on load weight.

This kind of measurement varies due to the case volume being different by brand, and the amount of bullet sticking down into the case - copper bullets stick into the case more than a traditional bullet, but the main variable is lot to lot differences in powder volume.

I’ve heard 2nd hand that multiple powder manufacturers say volumes between lots may vary by up to 10%. I’ve had a few lots over the years that weren’t that bad, but close so it seems reasonable.

 

[jjohnsonElknewbie]

H1000 was the primary powder I used with 6.5 SAUM. Case fill was never a problem. WSM case is bigger than the SAUM case so by deductive reasoning case fill will not be a problem. It seems Gordon's Mental Masturbation Tool is leading you astray.

H1000 and N565 seem to be the available temp stable powders for such cartridges but I bet N570 would look better than either from a velocity standpoint. 6.5 WSM is an overbore SOB and n570 would not be too slow burning.

Edit to add more: H1000 has been a good performing powder for me with heavies in 7 SAUM which is even less overbore and thus case fill would be even tighter. H1000, N565, N570, Retumbo is the burn rate range and powders I'd be looking at.

That's good to hear, and I'm happy to hear about your experience with H1000. I've had great experience with it in my 25, and will definitely give it a shot in the 6.5. Like I mentioned before, Gordon's has pretty low calibration for H1000, so that's likely why the numbers don't make sense.

For N570, Gordon's has max load at 75.5 grains with 105% fill, 96% burn, and 3193 MV.

Retumbo max load is also 75.5 grains but with 106% fill, 100% burn, and 3206 MV. However, calibration on Retumbo is as poor as H1000 in this tool.

Attached is the burn rate table I've been looking at to try and back into the Gordon's data.

 

[HuntHarder]

Fwiw, i have always had really good luck with hoggdon extreme powders and temp stability. I tend to try those first.

 

[wind gypsy]

Regardless of what Gordon's Mental Masturbation Tool says, i think H1000, Retumbo, N565, and N570 would all work well and not require heavily compressed charges if your chamber has adequate freebore.

 

[WeiserBucks]

Regardless of what Gordon's Mental Masturbation Tool says, i think H1000, Retumbo, N565, and N570 would all work well without heavily compressed charges if your chamber has adequate freebore.

I agree, mine liked Reloader 33 too. Slow powders are going to be the best performers in this particular cartridge.

 

[jjohnsonElknewbie]

Regardless of what Gordon's Mental Masturbation Tool says, i think H1000, Retumbo, N565, and N570 would all work well and not require heavily compressed charges if your chamber has adequate freebore.

Roger that and N565 is my preferred starting powder until I can test in the rifle. I have H1000 on hand and will see what it does as well.

N565

• 70.5 grains max load
• 3,196 MV
• 100.3% load ratio with 100% burn rate