Hello everyone, seeking information on an NY style engraved Colt

[Milio]

As stated on the Colt factory letter, this SAA was delivered to Hartley and Graham, N.Y, N.Y. in 1883 as 1 of a 200 piece shipment.
My best guess after researching the piece is that this is New York style engraving, likely done at Nimschke’s shop in NY.
There appears to be a “CB” or a “CR” or maybe a “CBV” engravers mark at the front-strap, I was hoping someone here might recognize it and shed some light, or thoughts on the engraving.
The piece is silver plated with dark and faded niter blue screws with period MOP grips.

Thank you for your time, and for your help.
Milio