whats nice about a muzzleloader is you can mix it up to get the results you are looking for. try mixing 4,5,6&7 1/2 shot to get the pattern you need. or you can shoot straight 4,5 or whatever. diiferent wad combinations will also change things, as well as powder charge. you also can put alot of shot in, but shooting can be a little hard on the shoulder. hit hte range and have fun!
I have heard that you should go 1 size up when it comes to muzzy shotguns.I use 4's but never had a chance at one.
Go for uniform groups and a size that goes thru both sides of a real tin can at the range you would shoot them at.
Equal shot/powder and even slightly more shot than powder is best.
The squirrels were getting stung with #6's this fall when I tried them.Quickly went back to 4's.
Pheasants fall using #6's and bunnies get #7 1/2's.
I use #5s,as far as max range that really depends on the gun and the distance where it stills throws a " killing " pattern.The velocity isnt much if any different between BP and modern loads,especally when you figure in the short barrels on todays modern turkey guns
i shoot 100 gr 2F, 1 3/8 of 6's. load goes like this: powder, 2 fiber wads, then a Winchester AA wad with the cushion cut off, then the shot, then another fiber wad. I'm shooting a TC Black Mtn. Magnum with an Undertaker choke. I have to remove the choke to load the gun, but it's worth it for the pattern it throws. I would like to go heavier but I don't know how heavy of a shot charge I can safely shoot in this gun, and couldnt get a definite answer from TC on it. So i stick with 1 3/8. That load has been good for 5 spring gobblers so far.