-I’ll be shooting no more than 100 yard/metre 13 shot matches, which is why I’m interest in not running big loads to help manage fouling over the string.
So the question then is how often are you allowed to swab the bore, or is this a timed event and you only get a chance to swab about every third shot? The reason is the slower twist gives you an advantage on fouling. They tend to be easier to reload as the bore gets dirty.
-The Barrel will be replacing an existing barrel in one of my rifles (Percussion Hawken) and I’ll more than likely have a custom rifle made built in the future.
-I pretty much have my mind made up on Rice Barrels. They seem to be on top from what I have read and been recommended. I don’t mind paying a bit extra for the best quality. Most of my more experienced Muzzleloading counterparts have recommended .50 cal with some recommending .54 cal. The main reason for those Calibres is just to help out in the wind a little bit more. I’m thinking about getting a barrel made in each Calibre.
Rice barrels are an excellent choice. 1:56 or 1:66 won't really make that much of a difference for the application that you've listed above. What you want is to buck the cross winds (if there are any) while at the same time have the lightest projectile vs. the powder load that you can, so you get the shortest flight time. Shorter flight time means less drop over that 100 meter distance. The odd factor, though, is the larger that ball, the more surface area for the wind to push upon, BUT the more mass, the more it resists the wind, YET the more powder you need to get that ball to a good velocity to Zip to the target and drop less and of course less time for the wind to effect the ball as well.
So a .440 ball with moderate powder will be moving very fast for you...but IF you often have good cross winds then it may not be the best choice.
.490 ball will need a bit more powder, but will resist the wind a bit more. You might find that sights can allow you to adjust impact enough to not require much of an increase in powder to compensate for mass and thus trajectory. It will be less recoil than from the larger ball.
.530 ball will need a pretty good increase in powder over the .440 ball to compensate for mass and trajectory. So the most recoil from the three but probably the best if you are in an area with good steady crosswinds all the time
So overall I'd say .50 cal shooting the .490 ball. Bucks the wind better than the .440, faster to the target than the .530 with the same powder load so less drop
One other thing to consider... there is one other slight advantage a .490 or even a .530 ball may have for you. The bigger the ball the bigger that hole in the paper. If you're using a target with a small scoring circle, or the 10 and X areas are small within the overall target, a .530 ball MAY cut the line between say the 9 and 10 ring and give you a "10" when the smaller balls might not when shot into the very same spot.
And there's one other
twist thrown into the mix.... since you're punching paper there's no need to wonder about terminal ballistics when striking a deer, etc. You're not concerned with that so..., you could go to an alloy bullet in .530. You could conceivably reduce the weight a bit by introducing some tin to the bullet metal (IF you hand cast) and develop a combination with that bullet plus a patch, to give you more speed, and the larger hole in the paper, though sacrifice a little on the ability to defeat wind. That's a bit complicated, but it would be shooting a ball weighing half way between the 177 grain .490, and the 224 grain .530...so with the alloy maybe a 200 grain .530 ball, fast, biggest hole of the three, and tiny bit less recoil than the all lead .530.
OR you could do the same by being an "oddball" (no pun intended) and get a custom barrel in .52 and shoot a custom ball in .505. May a bit too custom.
Sorry if I over complicated the response in the last two paragraphs. Simple answer... go with .50
LD