Martini-Henry 22 Conversion

Fellows I have picked up a Martini-Henry 22 Converted by G.C.Bonehill of Birmingham. It says on one side "Guaranteed British" On the left side plate it says "Converted by C.G.Bonehill of Birmingham for The Society Of Miniature Rifle Clubs" It is a nice weapon. Nice wood for it's age and a nice bore. It has a Lyman rear peep sight and a Redfield front site with hood. The top of the barrel near the breech says Ammunition 22. On top of the barrel near the venter it says C.G.Bonehill,Birmingham. I am going to take it to the range and see what kind of pattern I can get. Does anyone know about these weapons and what they are worth in good condition? It has a 29"barrel and is alleged to be a MK.i I can see very faintly on the right side plate Enfield. There are various proof marks. The serial number is 171xx The Mk.i was made between 1873 and 1885. These were converted between 1911 and 1913. They were used in the Zulu wars, the Boaar war, and in India and down under. Our troops are now finding some on Afganistan. Kyber Pass models. This is all I know. Any info is welcome.I can take some photo's Thanks