Damien, great to see you here again. I have always enjoyed and marveled at your skills. Best as it gets! Some really nice views I have not seen before.
As Sam says. I often stop and move the graver slightly back to make sure the cut is where I want it. I also never cut to full depth in one cut. I cut it shallow and then go over it a time or two and correct bobbles as I deepen.
I can only guess...I would think it was sculpted from the barrel steel but the smooth area on the leading edge sure looks like soldered on. Is there a breech plug?
I mostly do as Dave says...but I have posted quite a while ago using bronze spring material for trimming gold inlays that were set after the piece had been electroless nickel plated. The cavity and undercuts/teeth were done prior to plating.
Per your drawing...inline...as long as the slots are in line with each other they will look right. Brian's photo looks like inline to me per your drawings...they look just right.
As I understand it, the law requires a maker's name and location in addition to serial number on actions/frames. The removal referenced in the article applied to the lettering on the slide, an item that can be purchased with blank sides but Colt puts a lot of lettering on the slides.