I have two Hatfields, a .45 flintlock by Pedersoli and a .50 caplock.
I believe the .50 caplock was made by the original Hatfield company prior to the Missouri River Rifle Works buyout because it has a 1:48" twist and the 50 calibers made by MRRW supposedly had a 1:70" twist. The only markings on the gun are "Hatfiedd" and "WARRANTED" on the lock and "385" under the barrel.