gunpowders

[William]

On your first question, no, there isn't usually much moisture in BP but unless it is completely soaked it shouldn't affect your shooting.  That's the nice thing about traditional BP, it has a low ignition point easy to set off, whereas all substitutes have a much higher ignition point and it takes a lot more flame to get them going, plus they are much more hygroscopic, meaning that they will tend to absorb more water than BP. IIRC, Goex is coated with graphite which further prevents moisture absorbsion.  Please correct me if I've got that wrong.  As for the pressure changes associated with temperature, someone else with have to wade in on that issue.

[Blackfeet]

I have only used the pyrodex, as far as the subs go. I can confirm that that stuff sucks water like a sponge over time. I had one of those screw on funnels and didn't notice that the cap was cracked.Over three months it had clumped up solid.

[William]

I have only used the pyrodex, as far as the subs go. I can confirm that that stuff sucks water like a sponge over time. I had one of those screw on funnels and didn't notice that the cap was cracked.Over three months it had clumped up solid.

Yep, that's what happens to most substitutes but not traditional BP.  Some subs, Triple 7 in particular, are more energetic than Goex, so you must reduce your powder charge by 15%, so if your normal charge of Goex is 75 grains by volume then you'd use 64 grains of T-7.  You still can't use any of the subs by themselves in a flintlock, or at least without difficulty.  I have also noticed that the felt recoil and report is different when using subs as opposed to Goex.  Especially with T-7, the recoil is more of a kick as opposed to a shove, and the report is a sharp "crack", while Goex gives you a nice "boom".  I tried using the pyrodex pellets in my C&B guns years ago during a CAS match; talk about a disaster!  In my frustration afterwards I sold all of my percussion revolvers and started over.

[Otter]

As a side note on the use of Pyrodex. At a large BPCR shoot in New Mexico a friend of mine was using Pyrodex. I could always locate him on the line because of the pretty violet-pink smoke his .38-55 was emitting. Sorta hard to act the part of a salty plains hunter with pink smoke curling outa the muzzle of your rifle!! He quit using that product because of the very hard fouling that seemed to be a result. Or so he said... Personally I've had very mixed results with substitutes and good results with real black.