Remington never produced 16 inch barrels for commercial sales, but they have and do produce any length when requested by LE, Gov. and Mil. agencies.
If some of those barrels found their way onto the commercial market, the fault lies with the agency that resold, or allowed such barrels onto the commercial market. One of the manufacturer's sale stipulations is that LE/GOV/MIL agencies acquire these barrels for their use ONLY and not for resale. Commercial or otherwise. At least in Canada anyway. If it was sold in the States and made its way across the border, it made its way into Canada illegally.
Purchasing one of these barrels from the EE for instance, can be a slippery slope. Anyone can cut a barrel and sell it as a factory original by reasoning it was an agency manufactured barrel now in civilian hands.
As a civilian, unless you have supporting documentation of its original "commercial" provenance being an original factory barrel with a sales receipt from one of the agencies mentioned, I would not touch one with a ten foot pole. Even then, the agency is not abiding by the stipulations surrounding them and the barrel's legal possession and should not be selling them on the commercial market.