It was a shotgun according to the op--18 inches for those but otherwise correct.I was taught that the only correct way to measure barrel length (and the way used by the ATF) was to drop a rod calibrated to exactly 16.0" down the pipe and then to rake a straight edge across the muzzle to see if the dowel is below or not.
It boggles my mind how someone can hang out on a pro-2A site and presumably espouse a sympathetic view towards gun rights and then run out and call the police on a gun shop because a second hand shotty measures a smudge under 16" with a tape measure, like they were some kind of self appointed firearms consultant to law enforcement.
You potentially put this mans personal freedom and lively hood on the line over what? 1/32"?
I've had brand new tape measures fail cal at work by that much.
I'm stunned!
https://www.atf.gov/firearms/qa/which-firearms-are-regulated-under-nfa