Powder selection

[Pinecone]

There are other factors than burn rate.

Density of powder. A given powder may work based on burn rate, but be so fluffy you cannot get enough in a 300 BLK case to work.

[Dr.Phil]

Powder selection for any given cartridge is dictated by burn rate, charge density, and temperature sensitivity.
The powder choices for 300 BLK are also dictated by how much gas volume the generate if you are using an AR platform.
You choices go up exponentially if you are using a bolt action of Handi Rifle.

All in all, there is a pretty good selection of powders to choose from for 300 BLK.
viewtopic.php?f=141&t=86656
H110
Accurate 1680
VihtaVuori N110 Sierra Lists for subs and super sonic loadings for 300 whisper.
Hodgdon LIL'GUN
Winchester 296
IMR, Co IMR 4227
Hodgdon H4227
IMR, Co SR 4759
Accurate Arms 5744
Alliant Reloder 7
IMR, Co IMR 4198
Hodgdon H4198
Alliant 2400
Alliant 300mp
VihtaVuori N120
Accurate Arms #9
Accurate Arms #5
Accurate Arms #7
Accurate Arms 2015

Like most other cartridges, there are certain powders that just simply generate the best results for a given application.
300 BLK Supersonic loadings get excellent results using N110, H110, and Lil'Gun.
300 BLK Subsonic loadings get excellent results using A1680, RE7, & N120.