Everything seems to have been said but when I took my H&H 8 bore ball gun to H&H they said it was unnecessary that it had been Nitro proofed as the later (1880s?) guns (rifles?) were strong enough without, as the breech end was more robust

I am sure my Hollis .577 BPE at 12+ lbs would pass Nitro proof but prefer to use BP (or BPEq in the future)

I have a soft spot for I Hollis, having 3 rifles and an earlier Wm Hollis pistol, although most of their stuff was made by the Birmingham trade (W&S Scott especially for doubles)

MotelAlpha, if you can, please post pics and details (calibre/hammer[less] etc) of yours, it sounds very interesting!

I take it you mean the Duke of Connaught and Strathearn, 3rd son of Queen Victoria, onetime Governor General of Canada?

Some provenance!!

TH44