I emailed Mr Stimson about the Gunbroker and the pre98 trench guns.
Here is his response


Hello Brian,

I have very little research about High Standard riot guns. The only
research I have seen on them in print is Thomas Swearengen's book and
Bruce Canfield's book .

I do know enough to say that I can take issue with some comments in both
books. More in Swearengen's book because he says more. But I have not
tried to commit to paper those differences.

Unfortunately, the factory records a are not easy to use in the case of
their shotguns and since a lot of the early shotguns are not serialized
the data is not available in a serial number log.

I have found orders for police shotguns that were shipped with Service
Armament hand guards installed. I have found some that were shipped on
consignment to a few government facilities and I have found they were
returned and sold from the High Standard collection in 1980.

The two references you provided are ones I have seen before. One of the
accompanying stories talks about 1970's and a model that was
discontinued in late 1968.

I am skeptical about the two you referenced but I have not done
sufficient research to see if I can find say these are valid or bogus.


John Stimson