+1 to everything Hawg said . . . even if it does have a "southern slant".
I think that the only reason his kinfolk had "Union Cartridges" was because my kinfolk were a trapsing through the neighborhood and got careless and dropped some on the ground?
All kidding aside - Hawg has given you some good advice.
When I was shooting NSSA, i just filled the base of the minie with Crisco. You are going to really like that Enfield. I never owned one, but I shot a friend's during a 1,000 meter shoot we had one time up in Camp Grayling in Michigan. We were shooting on the 1,000 meter machine gun range with knock down targets that automatically popped up after being knocked down.
I have no doubt that Hawg can probably hit very well at 300 yards and beyond. With practice, you'll learn the elevation you need. We were shooting 60 grain service loads and were standing in rifle pits where we could rest the rifle over a blanket. During the shoot, I couldn't help but think of what it must have been like to be out on pickett duty and taking long range shots at the enemy. If i remember correctly, the targets were about 18" X 36". I did pretty well up to about 500 yards and after that, was able to hit a few at 700 yards after I figured out the cross wind. At 1,000 yards, they had a cut out of a full size horse out of 3/8 steel. I shot a number of rounds at that but only hit it once and if I remember correctly, I had to aim quite a distance above it. One of the fellows had a 44 Henry though and he hit the horse consistently - truly something to watch. U have no doubt that with some practice, Hawg would hit at 1,000 yards after the elevation and widage was figured out.
As Hawg mentioned, you can use a round ball and a patch but my experience with doing that was not too good. Most of these rifles have a shallower (if there is such a word?) rifling than a typical round ball barrel and usually they had a three land/groove rifling. In my case, I had a Remington Zouave I wanted to try it in for round ball deer hunting. The balls I had were .575 and my bore miked out at about .582 - .584. I tried a number of patching thicknesses and finally just gave up and used a custom built .54 Hawken that I'd made to hunt with.
I've shot a number of rifled muskets - originals and repros - the Enfield, Remington Zouave, Mississippi Rifle, '61 & 63 models and by far, the Enfield was my favorite. As Hawg mentioned, 60 grains was the standard load (Union) and that's what usually worked well in my rifles. Play with your loads and you'll soon find out what works best for you. Keep us posted on how you like it and how it shoots.
Hawg - I've heard and read about the difference in the service loads between the N and S - I also know that the south was forced to go to the extremes of collecting niter from outhouses, etc. to produce gunpowder. I've never read anything about the standard service load for the south at the beginning of the war but I would have to believe that since the Southern Army had many former Northern officers, etc. that their loads would have been the same. I always figured the difference was probably due to the quality of the CS powder not being as good as what the north was producing and therefore, an increased load was required. Your thoughs?