I'd bet $5 it's a sheriff's department like Lincoln County Sheriff's Dept., North Carolina. LCSD.

Give them a call and ask them if they ever did this to a handgun. If they did one.. they did more than one.

Check a county map of North Carolina and see if there are any other L-counties.

I wouldn't be real concerned about it not being the original number. Things aren't always so black & white on such matters. It now has a distinctive serial number. At the least it fulfills lawful requirement, possibly in a roundabout way.

Dutch