Engrave, Punch or Electro-Chemical Etching

Engraving or etching looks, or can look pretty professional.

Stamping usually doesn't, unless perfectly done as too alignment & depth of each letter.
And that's hard to do.

A lot of custom knife-makers use electo-stencil logos on blades, and it can look very professional.
http://www.texasknife.com/vcom/index.php?cPath=659_535

http://www.ecemmi.com/pdf/sf200fly.jpg

rc

Marking methods 300.

What does "0.003" ATF requirement" mean?

I assume it means that the marking method must produce uniform indentions in the metal that are 0.003" deep? If this is the case, then I would think that most forms of chemical etching are not viable. So now you're choices are primarily limited to engraving or steel stamping. If I had to pick between the two, I would choose engraving; it's easy to do neatly and professionally with a template.

I hope this helps.

Jason

The problem with punches is the possibility, however slight, of deforming the receiver unless it's very well supported.

Chemical/Laser doesn't always go deep enough.

FWIW we bought the bullet and purchased a used CNC engraver. We charge a flat $25 for standard "SBR/SBS" engraving (name, city, state) and give discounts for more than 5 units. PM if you're interested.

When D. L. Oefinger imported a bunch of Browning machine guns (without the right sideplates) back around 1980, he photographed the markings on the original sideplates before they were destroyed, and then photo-etched the markings back onto the new replacement sideplates that he manufactured. (At least that's what he told me.) I still have one of his guns, and the depth of the markings seems plenty adequate to me.

I wish I knew how feasible this process is on a small volume (and who would do it), because I have a display Thompson I would like to do this on. (Some of Philadelphia Ordnance's engraved markings are a far cry from the originals.) The problem is that it's hard to replicate the font, size, and spacing of the original markings unless you use some sort of photographic process.