Hi y'all,

I now truely discovered the fun of reloading and shooting the .45-70, as I've now been loading it with blackpowder and bullets I cast myself. I just LOVE this caliber!

The question: when reloading with BP, does it matter what primer I use? I'd think that BP needs only a spark to ignite (so any primer would do), whereas nitro needs a considerable flame AND some pressure.
(I just noticed I ran out of large rifle primers...could I use large pistol instead?)

You can try. It probably wouldn't hurt. I'm not a BP shooter, but I recall reading somewhere that the author said he preferred using large rifle magnum primers for better ignition. It might have been Mike venterino, but not sure.
Paul B.

Max, many of us use large pistol primers and an over primer wad of newspaper under the powder. This keeps powder from entering the flash hole and getting compressed in it. Most black powder likes mild ignition. No need for mag primers at all.
Pyrocrap and the other imitation junk needs hot fire.

My response is based on reading, not doing-so keep that in mind.

Paul Mathews has written several books on loading/shooting 45-70 black powder loads. He wrote that he drilled the flash holes of the cases larger than normal. I can't remember what size it was. The idea was to get more primer flame to the powder. I THINK he used magnum primers. Winchester primers evidently are hotter than some others, so perhaps Winchester Magnum primers may be the hottest.

Mathews did write that he keeps the 45-70 cases which the larger drilled out flash holes separate from other 45-70 cases. You will have severe pressure issues if you use the larger flash holes with smokeless powder.

I'd keep it simple. UNIFORM the flash hole, keeping it in smokelss powder safe-zone, then try standard and magnum primers.

I'm sure you can surf for some black powder cartridge rifle (BPCR) websites for more info on this.