Trapdoor Rifles

I have some 3F goex black powder that was given to me some time ago. I was wondering if that granulation can be used to load 45/70 and or 50/70?

Carlsr, You can its a bit stronger than 2FG due to finer grain size so just reduce your loads by 5 grains and it will shoot well.

Tom Trevor wrote: ↑Sat Mar 01, 2025 11:38 pm Carlsr, You can its a bit stronger than 2FG due to finer grain size so just reduce your loads by 5 grains and it will shoot well.

Thank you Tom!!

Although cartridges are listed as 45-70 or 50-70, they don't hold 70 grains of powder. Usually, guys list loads of 63 or 65 gains. The FFFg will give you a bit of velocity boost over Cartridge or FFg, or even 1 1/2 Fg.
I have shot FFFg in my flintlocks and caplocks for many years. Both .50 and .54 caliber. I remember an article in the Lyman Black Powder Handbook where they tested FFg vs FFFg in a.54 caplock. If I recall correctly, 70 grains of FFFg equated to 90 grains of FFg in their loadings.