Originally Posted By: PeteM

In 1912 the company moved to 6 1/2 Whittall Street which they named the Bisley Works.


Peter may have it here. Just guessing, but your example with non-rebounding hammers, sidelever, proofmarks, etc. would at the very least be pre-1887 and probably a pre-1875 with an altered set of tubes by "Bisley Works, Birmingham(?)(Rifle and Gun?)" post 1912 to 360 BPE, which would go right along with their pre-WWI relining effort, and you have modified 38-55 brass formed to the chamber. But why is it void of repair/reproof marks(maybe done during the War???)?

Kind Regards,

Raimey
rse