Smoothbores vs rifle muzzle velocity

[Dan Fruth]

I'm curious as to the difference between rifle/smoothbore muzzle velocity.

[Daryl]

I think the OP is thinking along these lines - or not?
Forsyth wrote that the smoothbore produced a higher velocity than did a rifle of the same bore size, and that his slow twist rates of 1/4 turn in the length of the barrel (normally 24" to 26" bls.)
also produced a higher velocity than did faster twists, then in vogue in Germany and England makes followed that 'drift'.
In our testing, of a 20 bore smooth bore and a .62 calibre rifle (barrels not the same length), we found VERY little difference when loaded with identical powder charges and patched balls. Certainly
not enough to make any difference on game.

[Dan Fruth]

Thanks for the reply. I'm curious as to the need for heavy wall thickness for rifle barrels vs smooth bore barrels.  Of course, the breech needs to be heavy walled, but muzzles can be thinner. Just looking at an oct to round barrel I did for a lighter gun.