What is used down the muzzle depends a great deal on the caliber. Old general wisdom was 3fg for 45 caliber and under and 2fg for those calibers above 45 and once we get to 75 caliber muskets perhaps even 1fg. In addition, frontiersmen frequently used charges that were about the same as the caliber, ie 45 caliber 45 grains and a patched round ball. 50 cal and 50 grains.
With modern steel guns and MODERATE loads, 3fg can be used in even a 54 cal.
Problem is that Americans in general always figure that if some is good, more must be better. So we have guys posting threads that they use 5 gazillion grains of flubadub powder and get 48,000 ft per second velocity. So some guy with a cheap muzzleloader hand forged in the Khyber pass goes out and duplicates the load and blows half his face off.
For white tail in eastern hunting conditions, there is no reason to use more 100 grains in any modern gun. Even less in a 45 cal.
There is also a point of dimishing returns. ie the powder burns slow enought that it isn't all consumed before the ball/bullet leaves the muzzle. The remainder is wasted in muzzle flash and causes increased fouling in the bore. For many short barrels 24 to 28 inches, in 50 caliber, that is right around 80 to 90 grains of 2fg powder.
There is another consideration. How far will you shoot? Some folks want to boost velocity so they get flatter trajectory. But under 75 yards, it really doesn't make much difference on deer sized animals. At 100 yds it may make a difference, but as the ball reaches sonic speeds, it piles air up in front of it causing a sonic speed ball to start out faster but decelerates faster over distance than a sub sonic speed ball. According to Lyman's Black Powder handbook First Edition, An extra 50 % of powder at 125 yard is only about 10 or 15% faster than the ball that starts out slower, with less powder. So the long distance benefits of the extra powder are (1) partially wasted in muzzle flash and (2)nearly erased by the effect of air piling up in front of that higher speed ball.
Now most hunters using muzzleloaders are using 50 caliber guns. Compared to 2fg powder, 3fg will generally burn a bit hotter, faster and cleaner, and with higher pressure in a 50 caliber. Some folks will figure a slightly smaller charge of 3fg for their 50 cal, than when using 2fg. and that is wise.
So, for my 50 cal long rifle, I use 4fg in the pan, and 80 grains of 2fg in the barrel. In my 58 caliber smooth bore, I use the same, whether I am using patched ball or shot. In the 45 rifle I use a 70 grain charge of 3fg.
All of these guns have barrels over 36 inches.
If it is going to be rainy and wet, I mix a little Lycopodium powder with the primer powder. (maybe 5%) It makes water bead up on it without soaking in. If you dust the lock area of the barrel and lock with the powder water will roll right off.
