According to my Lyman Manual for my rifle ... conicals in .50 caliber have a max of 100 grains of 2f or 80 grains of 3f as their recommendations. Before you get too excited, that is plenty of powder when shooting large conicals. One problem you might encounter is large conicals because of your twist rate may not shoot very well. Face it, for the most part you have a roundball barrel.

If I wanted to shoot something other then roundball I would look to two places. Buffalo Bullet makes a Ball-et in 245 grain that might stabilize just fine out of your rifle. All you can do it try. There is alsoa bullet called a PA Conical sold which is nothing more then a short conical.The other thing you might look or are Warren Minnies. Look for their lightest minnie. Also minnies have to be watched close.They are such a loose slip fit, the canat times work off the charge. For that reason I do not like them or hunt with the. With a slow twist rifle like you have, you want to keep your projectiles short in length.

I shoot a couple of slow twist rifles and have found the ball-et shoot well if you do not push them to hard. This is where I would look.

The other possibility of course is get a Great Plains Hunter Barrel for the rifle with the 1-32 twist and then shoot some big Great Plains Conicals out of that.