The Police Gun is a Greener pattern Martini Style action and not a Martini Henry.

The used full stock police guns when found are usually found in very poor condition. Look for a Greener Martini EG or GP shot gun or as Marrakai suggest a Martini Henry.

If you go with the Greener gun get one with out the split action for the take down barrel. The Greener also come with a safety, the Martini Henry does not have a safety. Also do not get a Greener GP that c-clips holding the pins in.

I have been told that I am now the proud new owner of a 577 2 3/4 NE. Haven't seen the gun yet but it is supposed to be on a Greener action.

I have a Martini Henry MKIV that was rechambered to .375 2 1/2 Flanged NE. This is the humpback military action. Shoots good, but haven't killed anything with it yet.

Another useful caliber in this gun is the Westley Richards Musket No.2 also known as the .450 Musket No. 2 or incorrectly the 500/.450 Musket No. 2.

A bit passe, but a useful caliber is the American 45/70.