I got several PMs about my flintlock as this is known to be the ONLY firearm I hunt with, the most asked question after where I buy my muzzleloading equipment is about the loads I use.
I have been shooting black powder guns for longer than I care to admit. Now on loads if you hang around black powder shooters for any length of time you will find that there are more answers to that question than grains in a can of powder. Or as my side kick likes to say, "It depends." So if it depends, then perhaps I can help with what it depends on. The first thing that it depends upon is whether you are target shooting, and this includes plinking, or hunting. The difference is really obvious. You never have to worry about a target running off, and targets taste terrible no matter how you cook them. Let's start with target shooting. Now the objective to target shooting is to produce the tightest group possible. Notice I said group and I did not mention score. You tighten up the group and the score will come with it. In fact there is a primitive match where the winner is determined by the tightest group. There are four components to every black powder load, the powder, the patch, the lubricant and the ball. Varying any one of these can greatly affect your group. Let's assume that you have a new .50 caliber percussion rifle. You've picked this rifle because the caliber is suitable for target shooting, plinking and hunting deer sized animals. Your first decision is what caliber ball to pick. With a modern gun the manufacturer will usually recommend a caliber. This is a good place to start. With a custom gun or such, measure the bore with a caliper and select a caliber about .005" less than the bore measurement. Now I am assuming that you already have a safe place to shoot, a comfortable bench to shoot from and, the gun will at least print on paper. If you are an excellent shot and never miss then you can skip the bench. I have only met one person like that and she out shot me all day long. The first thing you want to do is wipe the barrel and then fire a couple of caps, muzzle pointed to the ground, to clear any oil from the barrel. Next you must decide how much powder to use. For target shooting the best bet is to start low and work your way up. I'd recommend a starting charge of 45-50 grains for a fifty caliber. Yes I know it's light, but I have never had to a shoot an angry charging target. This is a starting load. Your next step is to select a patch and lubricant. I'd start with a .010 or .015 patch. Use cotton material only. Save the exotic stuff for the idiot down the road. Lubricate the patch, start the ball and patch down the bore and seat them with your ram rod. My lubricant of choice is spit. Works good but at times the patches taste terrible. Kind makes you wonder where they've been. One thing about spit, it's tough to run out of. Okay, now you're ready to shoot. Before you shoot, remember, you're not interested in anything but your group. If you're on the paper, your doing fine. After each shot wipe the bore with a damp patch, then a dry patch. When you reload, try to seat the ball with the same pressure each time. Make sure the ball is seated on the powder. (A marked ram rod is handy for this.) Don't beat the ball into the powder, just seat it firmly. After shooting five good shots that means no flinching, eyes open, etc., collect your target. Here is where the fun begins. By varying your load, patch, and lubricant you can adjust your group size. Some guns shoot best with tight patches and grease lubes, other do better with looser patches, spit lube or lighter loads. The secret to success is to experiment and be consistent. Now I can help guide you on some of this, but the rest you have to do yourself. In my experience most black powder guns do well with a snug patch and ball combination. Snug is when the ball and patch can be started by hitting your ball starter with a sharp smack from your open palm. If you're a lady, a light tap from a plastic hammer head. If you have to beat the ball and patch in, then your deforming the ball. A good way to judge is to retrieve your patch, although this nearly impossible at a well-used range. Look for cuts in the patch, a sure sign that the patch is too tight. Also look for burned edges, a sign that the patch was too loose. Anything in between is good. I always start by varying my powder load, usually in five grain increments. I like to shoot five to eight shot groups. After each group I remove the target and mark the load, patch, lubricant on the target. These become my reference points and records. Ideally as you work through heavier loads, you will see your group tighten up and then widen. Sometimes you have to try lighter loads, but usually it works the other way. When you get to the point where the group widens, then the previous load was the best. Shoot another group at the best load to verify your assumptions. By the way I have never had a target charge greater that 70 grains in a .50 caliber rifle. If the gun has a lot of recoil then your way too heavy. Lighten the load. After I have determined the powder charge, I start varying the patch and ball combination. Depending upon how tight the original combination was, I might try slightly heavier patch material or a different type. Sometimes a pillow tick seems to work better than straight patch material. If I see an improvement, using my best powder load, then I try a lighter patch and slightly large ball. Or at times I go the other way. Each gun is different. Finally I vary the lubricant. Remember always try to remain consistent and keep a record. Working up a load is an easy but time consuming process. Of course and trip to the range is better than yard work. It may take several trips to the range to get close and a lot more to get the ultimate group. But with your gun holding a 3/4" group at 25 yards you'll be one step closer to that 50-xx score.
Now this is only my way of thinking, if you ask another longrifle hunter (and by that I mean (blackpowder) they will most certainly have their own thoughts. Another good wolf pack member to ask would be FVR as I know he has a nice looking muzzleloader, or Medicine Wolf cause he, like me, only hunts with flintlock muzzleloader.