I have been reloading 30/40 Krag and .303 Brit with IMR 4895 but its impossible to find that powder, there is local store stocked with alliant powder but hard to find info for these calibers, they thoughts would be great
The problem with that is that all those powders with similar (308/223 suitable) burn rates are sold out. 4064, Varget, N135, TAC, 335, 2520...etc I have not seen any of those for months, now if you needed something slower burning RL19, 4831, and MagPro are everywhere. Good time to own a high intensity magnum bad time to own a 308 or any classic (except a 6.5x55)
one of the reasons i finally purchased a 45-70 is because you can substitute black powder directly into that cartridge by stuffing it full and putting a bullet on top. i know that doesnt help your issue with the 303 and such. its in the same class as the 30-06 and 308 powders that work in those should work in the 303
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." — L. Neil Smith
The problem with being stupid is you cannot simply decide to stop doing dumb things...
"I crapped my pants to avoid the draft!!" -Ted Nugent
Only reason I can keep feeding the 30-06 is nobody knows how good RL19 can be in it, it seems like too slow a burn rate but I assure you it works like a charm. There might be something that you could use like H380 or Big Game both of which use and have seen recently.