An Allen Wheelock drop breech in 44 Henry. Aggressive 25 twist, 430 groove, 411ish bore. 3 lands and grooves.
Converted the breech to centerfire from rimfire using Uncanny American Savvy.
Rechambered to 44 special. Case head the same (or "close enough") so no extravagant extractor work.
Used the 200gr FN bulllet mold I got here. Charged a case with FFFg less enough to seat the bullet, and voila.