You are correct Miller. A P toplever hammer gun refinished by Brad Bachelder.

The Parker Lifter era and toplever catalogs only listed 'English Twist' and (later) 'Fine English Twist' (Belgian sourced) but ribs were marked 'Stub Twist', 'Plain Twist', and 'Twist'. Damascus-twist is rarely seen.
I am of the opinion (worth nothing) that Lifter twist and damascus WAS sourced in England and the stock used up after the toplever hammergun was introduced, which used Belgian rough forged tubes.
A pre-1874 Back Action Lifter with '3 Stripe' damascus and Birmingham Provisional Proof

I'll probably start another thread about Damascus-Twist