Discuss your options with John Taylor, as he is very knwoledgeable. But, I think from what you are describing, a 32-33 inch barrel will be about perfect. Most modern gun shooters only handle a 30 inch barrel on a Shotgun, and then only if they are Trap Shooters. Barrels longer than that are just a mystery.
With BP shooting, using iron sights, even if you choose a peep sight, because of your eye sight restrictions, the long Sight Radius comes in very handy. However, you also need to carry the gun, so weight becomes a factor, and you have to lift the gun up to your shoulder, and hold it there for off-hand shots. Balance is critical.
I do not currently own a gun with a barrel that small in diameter, but I once owned a small barreled .45 caliber that was only 25 inches long. It shot fine, but if there was any kind of cross wind, it was hard to hold on the target. I would have appreciated more weight out there in front of my forehand. Adding another 7-8 inches to what I had then would have made a great bit of difference to the balance, and handling characteristics of a small bore rifle, IMHO. I have handled small caliber rifles that others own, and with that small bore, the barrel will have plenty of weight on it, to give you some "Muzzle hang" for off-hand shooting. However, I would not overdo the length. Its not needed for such a small caliber gun. Your powder charges will run from 15-30 grains of 3Fg, and even with what seems like a fairly small amount of powder, that ball will leave that muzzle with plenty of zip.
The restrictions on using a .32 cal. MLer for hunting come from the fact that the RB is so light in weight, and the Ballistics Coefficient for the .32 simply won't let the RB buck any wind over much distance. For most hunting, these are 25 yd. guns. On calm days, I have seen .32 shooters take the center out of 100 yd. targets, shooting off a rest. Regardless of caliber, Iron sights( open) and the terrible Ballistics Coefficient for Round Balls limits most MLing rifle shooters to 100 yards or less for most shots at game in the field. The larger caliber balls are more than capable of killing many times farther than 100 yds., but the problems of accurately estimating range, and the steep trajectory you deal with as the yardage increases makes it more difficult to hit targets accurately at longer distances. I watched my Brother, shooting a new rifle, in .45 caliber, hit a bang plate target at 130 yards at a club, many years ago, now, and he missed the target twice by holding up too much front sight- shooting over the plate. The plate was about 16 inches in diameter, suspended from chains so that it swung back and forth when hit. His third shot finally hit it about 4 inches below the top, for a satisfying "bong". Because of its size, he thought the plate was further away, and held more front sight up than was needed. That is the kind of problem that range estimation causes for any iron sight shooter.
Have fun with that underhammer. I know you will like it, and you will find its a very accurate rifle. :hmm: :thumbsup: :thumbsup: :hatsoff:
