The engraving looks of less quality than I would expect from a Best Grade. It's certainly not anything special as far as the scroll cut quality/style nor the additional cuts like the border(s), fine line shading and the accent cuts around the scroll groupings. The latter is very crudely & quickly done.
The one thing that really stands out to me is the bbl address.
Two things about it:
#1...The lettering is to be kind, not of professional quality. Certainly not something for a Best Quality firearm.
Letters are mishappen. If the engraver put down guide lines to letter, they certainly weren't followed closely at all.
#2,,, and this is an Engraver's thing,,it looks like the person that did the engraving of the lettering orig lettered it as :
.....73St James Street
Then realized or was informed of the mistake and
added/squeezed in the 's on to James to form James's
The way out of wack spacing betw the James's and Street is almost a sure sign of correcting a mistake in the lettering.
The other thing it can point to is that it was done by a #1.
By comparison, the lock plate lettering looks better. But there is little of it and it is harder to see in the pic.
Just some things that I see. Simple observations.