This - quoted from George Madis' 'The Winchester Book' - long considered to be the 'bible' of the Winchester Collector.
From Chapter 7:
"Various loading methods were developed and patented in 1865 and 1866. James D. Smith of Bridgeport patented his hinged loading gate located at the bottom of the receiver, on February 27, 1866.
Another type of loading system which was developed was the Briggs Patent device for which Patent number 58937 was granted on October 16, 1866. A sliding fore end, often of brass, exposes a loading port in the magazine tube. A modified system of essentially the same construction was used for the arms which have a sliding magazine tube.
as far as is known, no arms using these devices were sold commercially, and each gun differs from the other specimens in many features. Receivers of the Briggs models are of the same type as were used for the first model of 1866 having King's improvement, and have serial numbers in the 13,500 series, while earliest arms having King's improvement bear serial numbers in the 12,000 series.
Exactly why Winchester purchased and made arms with the Briggs patent loading system is not known, especially since the superior King's improvment preceded the Briggs, but it is likely that Winchester wanted to eliminate the possibility of a rival manufacturer using it."
The suggested reason behind Winchester's purchase of that patent is most likely valid.
The firearms trade was getting fiercely competitive and larger manufacturers would either purchase smaller ones (especially those with usable patents but no capital) or would drive them under.
As to the HRAC version 'Henry' - as has been said - it's a copy of something that never existed - and its place of manufacture has zero bearing on anything.
They should never have used the name 'Henry' as it intimates a relationship with the original - but maybe that's exactly why they did it....
As to the Model 1866 being more like the Model 1873 - sure - when you think that both use a lever system and have a wooden fore end and they're 'shaped' similarly, they have a lot in common, since the Model 1866 was Winchester's distinct 'product improvement' version of the Henry and eventual changes in manufacturing would see it develop into the Model 1873.
As to the question that started this - 'in common use' would apply - and they just weren't.
Scouts Out!