The Greener GP ...isn't a high grade gun, doesn't have two barrels, and isn't much regarded by collectors. So I have no excuse for this post other than an unseemly public display of a private obsession, one of the few you can't be arrested for. So far.
The GP is the shotgun version of the Victorian Martini Henry military rifle, the British equivalent and contemporary of the rolling block Remington. Both were immensely strong and practical soldier proof weapons.
If you ever saw the movie "Zulu" it's the one used by the defenders of Rorkes Drift. At middling range it was absolutely devasting; firing a very heavy 45 cal soft lead bullet from a necked down (.577" ?) case, the wounds inflicted were descibed by observers as "horrific".
Already a long weapon, with a 24" bayonet it actually outreached the Zulu warriors stabbing assegai. The Zulus who had more courage than was good for them, were willing to take many casualties from rifle fire in the initial charge in the belief that they would be superior in close quarter battle. Colour Sergeant Bourne (Senior NCO at Rorkes drift) said in his memoirs that he didn't believe that any of his men (excepting the debilitated and defenceless in the hospital) were even so much as wounded by assegais.
The gun appeared in dozens of variations as per this site
Jasons Page Note the author's comment about the safety on the shotguns he shows....the big Jessie! It's a doddle.
The underlever falling block action was originally designed by Peabody, an American, and refined by Martini, a Swiss who rendered the mechanism hammmerless; Henry needs no introduction.
In it's shotgun reincarnation the Greener has three drawbacks. It doesn't like plastic cased ammunition, the stock shape is a shoulder buster, and the later versions produced by Webley and Scott post Greener's demise are poor...very roughly finished.
Get a nice Mk 1, fit a pad, use paper cases and you have a delightful gun. First class handling, great pointability, and just about the fastest single shot action of the lot...I'm up to twenty a minute aimed shots at clays (which is a long way from twenty hits) brilliant for flighted pigeon and duck.
There, I feel better now. Nurse, the curtains please!
Eug