Use WW748 for .300 Blackout loads?

[trooperdan]

I have a good bit of WW748 and a new .300 BLK I just built. Has anyone used 748 in loading for the BLKJ? Or could anyone with Quickload give me a start point for a 125 gr J-word? I know H110 and L'il Gun would be the choice but, darn it, I have a lot of this powder I want to use!

[427smith]

Hav'nt tried 748 but I had no luck with H335. some charts show 748 slightly faster and some show 748 slightly slower burning. A heavily compressed charge left lots of unburned powder, fired casings showed many powder dents. I even tried mag primers and a heavy crimp. also velocity was down 100+ fps from RE7. boolit was 155 GC BRN 18. for what it's worth

[jmorris]

I think you will have better luck with magnum pistol powders than rifle powders. Not much case volume in the necked up .221 fireball case.

[rockshooter]

With that light a bullet, 748 is probably going to be way too slow a powder. I tend to use faster powders- like H110 with bullets lighter than 150 grains and a little slower like 1680 for heavier ones but 748 just seems way too slow for 300BLK
Loren