If you use Orion Arms, they will require the lower to be stripped. I have used them once and am about to send another lower to them. Their turnaround, at this time, is about 3 weeks from receipt of lower. Cost, for three lines of engraving, is $45 with $15 for return (insured) shipping. They have much experience in doing NFA compliant engraving. Not something I want to risk with an inexperienced engraver.