Pete:
If I'm following your line of thinking here your take is everything but the barrels for the 1883s were produced in Hartford. This would be in agreement with what Kathleen Hoyt told me when I spoke to her several years ago.
I never asked specifically about the barrels as I assumed Colt had imported then as did most of the domestic shotgun manufacturers.
N.B: Inre. to the British proofs on the Colt barrels. If a British Company imported a Colt Shotgun it would have required proofing before it could be sold just like any British made shotgun.
Jim

The 2nd Amendment IS an unalienable right.