Little help with interpolation, makes no sense to me...

[Wannashootit]

Couldn't find H1000, so I'm having to re-do load development for a .338 LM with Retumbo and Vhitavuori N565.
N565 was specifically developed for the 250 g

The Vhitavuori load data is very confusing to me.

280 gr. Barnes: 69.9- 79.6 grains
300 gr. Berger: 75.5- 85.6 grains

Now, I'm not the most "sophisticated" reloader, but almost universally the heavier the boolit, the less powder used.
I understand that some (or all) of this may be related to the loaded length and the fill density/compression in the case.

So WTF to do, when the specific bullet you're loading for (in this case, the 285 ELDM) isn't listed- run with the 280 gr. data?

 

[FLIGHT762]

If you have the Barnes 280 gr. LRX, it is a monolithic bullet. That's likely why you're seeing the different powder charges.

 

[Huskydriver]

Start low and work up

It's not just bullet weight but also bearing surface that effect the pressure

 

[KnowNothing256]

If the Barnes is monolithic and the Berger is lead core, good chance the Barnes is longer. Copper is much less dense than lead, so yeah, I’m guessing the Barnes is eating up more case room.

Good call, @FLIGHT762

 

[Wannashootit]

If you have the Barnes 280 gr. LRX, it is a monolithic bullet. That's likely why you're seeing the different powder charges.

Thanks, good catch- it is the LRX, wasn't aware that is a solid.
It's still odd that they list a 285 grain Hornady HPBT- which would be close to the ELD-M, with four powders and N565 isn't one of them, but they do list it for the 300's. Far as I know, if it works for 250's, and 300's, should work for 285's.

I'll use the info for the 300's should be close.

 

[Hawk in WY]

Watch for cartridge overall length used with VV data. They test to a European standard with some cartridges. Some are loaded very short which makes the data seem odd.