TABS is correct, it is a false muzzle.
It aid in loading in that the pullet is centered before making contact with the bore. I have a Schutzen muzzle loading rifle with the same attachment.
The pistol is a one of a kind, hand built, target pistol. It was special ordered and took 3 years to complete.
Built for Bob Schmidt for the Ca. Black Powder Championships back in the early 70s.
Here are pictures of the muzzle.
TABS: thank you for the offer but you might be just a tad low.
Cheers
