I got away from using pistol and shotgun powders for cast bullet rifle loads many years ago.

I'd tried a load straight out of a book for the Trapdoor Springfield .45/70, in my .458 2" and achieved a pressure excursion with it. I had loaded only 5 rounds and pulled the remaining 4 after firing that 1st one. Absolutely no chance it was a double charge, either - I double checked each one, first visually, then with a 3/8" dowel. I didn't use a filler, either. No hard done, but the report was rather sharp and the primer pocket was expanded. How that can happen with around 25gr. (which is actually a .44 mag load) of powder, I don't know. Detonation?

Anyway - I switched to rifle powders that allowed much higher speeds at reduced pressure with good accuracy. H4895 became my favourite as I seems to work well right down to about 50% of capacity with better accuracy than IMR 3031 & 4198. H4198 developed pressure that required heat treated bullets at 2,000fps, whereas H4895 worked well with straight WW metal.