There are rumors of a limited run of No5 rifles being made by the Long Branch facility.
We had this discussion on CGN about a decade back.
One of the members, now banned? Derek Snowdey had one with all LB stamps. Claimed to have purchased it from a business in Toronto over 20 years previously and that there were a few dozen of them there. All were New In Grease, in cardboard boxes.
The rumor was that LB did indeed produce a very limited number of No5 rifles, which would make sense because there was also a rumor going around that No5 rifles would be replacing No4 and No1 rifles still in the system. This never happened, because all of the major powers were getting semi auto rifles.
In the case of milsurp rifles, never say never. A couple of hundred non standard rifles wouldn't have been considered to be a production run, but could easily have come about to create test beds for evaluation.
Still, tiriaq is correct in that there is no definitive proof that LongBranch ever made a production run of No 5 rifles.