Hey George,
There are a lot of things that go into developing an accurate load. Velocity is just one of them. Any load that makes that crack will absolutely deliver the round ball to the 100-yard target with less drop than a load that goes boom. But drop is just one part of developing an accurate load.
The best way to find the most accurate load for your rifle is to go to the range and start shooting at a close target (12 to no more than 25 yards away). With a 50 cal. start with 50 grains of 3F black powder and fire 5 shots. Check the grouping and don't worry about placement yet. Then increase the load by 5 grains and shoot 5 more shots. After you get a good grouping, then you can adjust your sights for left/right placement. Don't worry about shooting low or high yet. Continue adding 5 grains until the grouping starts to open up. At that point the added velocity is no longer helping with accuracy. So back off by 5 grains and use that as your standard load. Odds are your load will be somewhere between 70 and 95 grains.
Now try shooting at the 50 yard target and see how your groupings look. They will probably be similar. Finally shoot at 100 yards and check your grouping there.
One inescapable fact about higher velocity round balls is that they drop less at 75 and 100-yards than a slower projectile. The ball actually drops at the same rate with all loads but because it gets out there much faster, you will see less drop at 75 and 100 yards with a high speed load (cracks) than you will with a low speed load (booms). Difference can be as much as a drop of 6 to 8 inches versus a drop of 4 to 6 feet with the slower ball.
Presuming your groups are pretty well centered, this is the point that you decide where you want to zero it in to. If you are only going to be making shots at 50-yards then it makes sense to zero it in at 50-yards. However, if you do that, and you need to make a longer shot, you will find that it drops drastically over the next 50-yards.
Wherever you decide to zero it in, be real sure about your decision before you start filing down the front sight to get it to zero. Once it's filed, you'll have to replace the sight if you want to zero it in at a shorter distance.
Personally, I've sighted my rifle in so it hits dead on at 100 yards. It shoots about 1" above the point of aim at 25-yards, 2" above the point of aim at 50-yards, and dead on at 100-yards. That way any shot I take within 100-yards my round ball will be within 2" of my point of aim. That's a killing shot as long as I do my part. One of my rifles likes 80 grains of 3f powder and the other likes 95 grains. I get between 1800 and 1900 fps out of those loads. It just depends on the barrel of your rifle.
A lot of people will shoot a little heavier load than the optimum load for accuracy when they are hunting because they want the extra energy at those 75 to 100-yard shots. The round ball bleeds off energy and speed like crazy and they'll sacrifice a little accuracy for the extra energy delivery to hopefully make a cleaner kill shot.
Some folks work up two different loads, especially if they are going squirrel hunting. Squirrel hunting is done at much closer ranges and most shots will probably be within 25 yards. so they shoot at a 25-yard target and typically use 1/2 the powder they would for big game at longer distances. At those short distances for small game, you don't need the heavier load to send the ball accurately only 1/4 to 1/3 the distance that you would need for deer hunting. And you certainly don't need the energy to kill a squirrel that you do to kill a deer. Plus, less powder means less $$ spent.
Here's a link to an online muzzleloader round ball ballistics calculator. You enter in the size of the ball (it automatically adjusts the weight) and the distance you want it zeroed in for and it tells you the results you can expect. Play around with that Muzzle Velocity (fps) and see what the differences are in drop. Take a look at the energy column too and you'll see how drastically the energy bleeds off by the time you reach 100 yards.
http://www.ctmuzzleloaders.com/ctml_experiments/rbballistics/web_apps/rb_ballistics.html
You can download the program from their web site too from the page below. It allows you to print out copies and/or keep them in Word or Excel. Here's the link:
http://www.ctmuzzleloaders.com/ctml_experiments/rbballistics/rbballistics.html
Hope this helps some,
Twisted_1in66 :thumbsup: