The scroll work looks German or Austrian,,or at least done by someone who learned from an engraver from there. The work was done after the conversion I suspect from the way it is wrapped around the (registered trade marked) bbl markings.
Many engravers from Europe came to the US after WW2 as there was at least a working economy here along with a market.
Many that stayed in Europe found work from some of the larger enterprises like Kurt Jaeger. His firm did alot of work for US gunsmiths, dealers and collectors. Their market in Germany after WW2 was limited early on the US Occupation personel.

Most all the work from his shop will be marked with the 'Kurt Jaeger-Mainz' name, though he had some of the best of the German engravers working for him,,Willig amoung them. Erich Boessler may have even engraved for them after the War too.

There are many freelanse engravers in that era that cut in that scroll style.
Most all would have signed their work, though it can be sometimes small and difficult to see.

Beautiful revolver! Relief work is time consuming.