If this gun was one of the official items from the government collection, the Controller of War Throphies records will show make, calibre, and serial number as well as where, when, and by whom the gun was captured. It may also indicate the dates the gun was transferred to the UK; what ship was used to bring it to Canada, and where it was stored before being awarded. (i.e. Canadian National Exhibition, c.1920)
Perhaps the record will also provide details regarding the burst barrel? It is quite likely the Canadian War Museum has the original record.
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It would be intersting to see why Bracebridge received a 77, vs a larger gun. It may be related to the number of war dead from that particular area, but the award may not have been limited to this single gun.
With the 100th Anniversary approaching, would it be an appropriate time to clean the gun up and display it in a prominent location with the Bracebridge Memorial plaque?
Patriotic enthusiasim appears to have time limits.