I don't know where Joe does his but I usually do them in the same location as Orion although if the info is short enough I have been able to fit it on the right side of the mag well on all but the MKE guns as ATI has pretty much cluttered up all of the space on theirs. I have also seen them done on the top of the receiver and in the stock channel.
They certainly do good work. They have done (redone in two cases) all 4 of my SBRs and when they say it will be .003 or more deep it will be (which is why they had to redo two of my previously done SBRs whose engravers apparently did not know how to measure depth). Great company and I have always had very fast turn around times.
I have mine engraved only on the flat flange at the rear of the receiver. Many builders mark them there, and I've never, ever heard of improperly located markings. Orion is being overly cautious on the whole "conspicuously marked" clause which is why I personally would never use them. As long as it can be made visible without the use of any tools whatsoever, it is acceptable. If it literally had to be 100% visible 100% of the time, then the markings on the top spine of the receiver would be illegal, as they are covered up when a scope mount is installed. And even then, some of them require tools to remove, and it's still not a problem. If it can be easily identified upon inspection, it's fine.
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