For .45 Colt Open Tops, what is the best bullet shape and weight?

[Long Johns Wolf]

Lefty Dude: my Centaure breech loading conversions all have liners fitted to their barrels of .429 dia rifling groove dia. Hence I load .428/.429 dia 200 grainers of 16 BH in them over a light CAS charge of NC powder.
Only the Thuer front stuffer is equipped with the factory issued C&B barrel of .446 rifling groove dia. For reloads I am using soft lead bullets of heel type design and .451 dia, ca. 200 gr. over CH2 or CH3 black powder.
Long Johns Wolf

[rifle]

I may as well go back to the old tale of lead bullets shoot best when right at the barrel groove diameter  or .001-.002 inch over that groove diameter. Too loose leads the barrel, too tight leads the barrel and both those don't shoot as well as a gun usually can. The experts in the gun mags of yesteryear used to relate that a gun may or may not shoot well or have leading problems with the .003 inch over groove diameter bullets. That always seemed too tight to me using conicals.

Round balls? They can go with a bigger diameter than conicals because of the ease they swag into the barrel and make a smaller band around the ball when looser and a wider band around the ball when tighter. Guns can shoot well with balls and shallow grooves as is seen in the high dollar target guns cap&ballers like Hege and Pedersoli sell for example.

Centaures usually have the shallow grooves in the barrels for a good seal I'd say. If I was in LeftyDudes shoes I'd be thunkin bout getting an expander in my expander/bell die that would expand the inside of the case a little less and use the pure lead 200grainers sized at .448-.449 whichever corresponds to the majority size to the grooves in the barrel. Try .002 over groove first and then if experimenting is fun to the Hombre try the .001 over groove.

Anywhooo..the company CH Tool and Die/4D Custom Die Company in Mt. Vernon Ohio sells expander dies that can have any size expander inside an Hombre wants and most likely would make a size die to make bullets the right diameter. 1-740-397-7214

Lee Precision sells these size dies that go in a press and the bullets are pushed thru the size die from the bottom upwards. Lubed/sized/lubed again. The bullets collect in a red plastic jar they enter from the bottom. Cheap and works. Those size dies can be honed to make odd sizes.
I'd imagine Bernie Rowls at Old West Moulds would alter a standard size die to what someone wanted.

NEI makes any type size bullet mould an Hombre would want. They have a good 45-180  #284A and a 445-208-LC  #271A that's a heel bullet that could be sized. "NEI Handtools" has a web site. The moulds run a little more in diameter so they can be sized.