I’m building an SBR using a factory-Cerakoted FDE Aero Precision lower. I usually have my SBRs engraved on the right side, above the trigger pins, using a font about the same size as the factory markings. I’ve never cared about “hiding it” that much, and it doesn’t really stand out in that location, anyway. A little Al Black and it pretty much disappears.

So, my question is: will laser engraving (THSF has been my go-to) burn through the Cerakote into the Aluminum, leaving raw, shiny aluminum?  I don’t know the nominal thickness of Cerakote.

Here’s my dilemma:  if it does leave shiny aluminum, my choices are silver (ugh) or using Al Black, and ending up with very distinct black-on-FDE lettering on the side of the receiver, which I’m not hot on.

If it doesn’t, i.e. the .003” engraving is less than the nominal thickness of the Cerakote, we’re good to go with engraving over the trigger pins. If is DOES, then I’ll probably have it engraved inside the trigger guard, all stealthy-like, to minimize the black lettering.

Anybody know?

If it doesn’t get into the metal you’re not engraving it. Or am I misunderstanding you?

Exaggerate for a second, and assume that the anodizing (or Cerakote, or Melonite, or whatever) is .25" thick.  (Boy, that's thick anodizing, but stay with me).  Engraving depth requirement is .003" ("For firearms manufactured or imported on and after January 30, 2002,
the engraving, casting, or stamping (impressing) of this information must be to a minimum depth of .003 inch.")  In this extreme case, engraving to a depth of .003" would not penetrate the anodizing.  That concept is the genesis of my question.

Which is why guns are engraved before they’re anodized. Everything I’ve read on here and elsewhere said the depth requirements apply to the actual surface of the gun not the coatings that rest upon it.

IE if the requirement is .003 then you have to burn through the anodizing and go .003 into the metal.

None of the NFA engraving I'm aware of (for Form 1 type NFA) is engraved prior to anodizing.  How exactly does one measure the depth of anodizing to know you've gone "anodizing plus .003"?  Just burn extra deep?  Serious question.

I laser engrave NFA stuff.  The engraving cannot simply be cosmetic, which is what it would be if it were "just in the Cerakote" finish.  We also Cerakote.  If applied properly, it's not thick enough for there to be enough thickness to get a good engraving in it without getting at least a little of the metal exposed at some point.

If raw aluminum or Aluminum Black aren't your thing, you can have the lasering done with a masking, then shoot the engraved area with Cerakote.  You just have to have the right masking material.  Anyone who laser engraves metals for decorative purposes should have such masking on-hand.  In all honesty, the aluminum and the FDE may not be all that disparate in intensity to make it stand out a bunch, but it depends on which FDE you have.  A darker one (Glock FDE, for example) will allow the silver to show better than a pale FDE.  It's still going to show, just depends on how much it bothers you.

ETA:

Yes, we just engrave the stuff deep to (a) ensure we are waaaay past the minimum and (b) ensure that if someone gets a 4 color Camo job put on it, the engraving doesn't get filled up with Cerakote during the multiple coats and is still visible.

Yeah, I should have thought of this first.

Thank you for this.  I'm leaning toward small lettering in the trigger guard.  I appreciate the help.

If it i does not cut the metal, you are not engraving the "firearm frame, receiver, barrel or slide". You are engraving the finish.

You send it to a competent engraver who knows how to do it the the proper depth. I went to Ident, they showed me how they can measure the depth to prove it meets spec.

Could engrave it and then just fill in the engraving with paint to cover the bare aluminum.

Engraving over Cerakote to get proper depth in the metal is no problem, find someone that knows what they are doing, mine engraved even deeper than required. I engraved an ODG cerakoted receiver and Aluminum  Black was used afterwards and the engraving is barely noticeable and it is deep. I also had mine engraved in the trigger well.

Laser engraving will go through actual anodizing nicely.  My engraver, Gray Laser Engraving uses a proprietary chemical to darken the bright aluminum exposed by this process immediately after engraving, so it's as dark as if it had been anodized after that engraving.  Mr. Gray goes WAY past the 0.003" minimum depth, both for compliance and for readability.

Lasers go through Ceracoating too, so aluminum black (if applied immediately) will darken the metal exposed by the laser.  Heat helps aluminum black chemicals work more effectively, and since Ceracoat is baked on, using a heat gun on the engraving shouldn't hurt anything.