Rolling Block Carbine Barrel Dimensions?

[Fishoot]

If anyone has a rolling block carbine I would appreciate it if you could measure the muzzle diameter, rear diameter forward of the barrel extension and maybe a midpoint diameter. No matter what country it was from, but need it for .458 or larger. If the barrel is a straight taper, that's good too. I am cutting a taper on a 45-70 barrel and need original dimensions to complete a barrel 18 1/2" in length. Thanks for your consideration.

[superc]

My 43 caliber Rem LB Carbine with 20" bbl is .982 at the breech, .760 at the tip of the forehand grip and .649 at the muzzle.

[superc]

Don't forget there is a lug on the bottom for the forend stock.