As I have been a member of this forum for several years but have not posted. Just learning from all of you.  I have been redirecting my collecting from WW2 back mainly Mausers, and older US.  to Single Shot breech loading cartridge rifles. I have been lucky enough to obtain quite a few Remington and Stevens Rolling //Falling blocks with a few Martini-Henry's, German Schuttzens, a few Ruger#1//#3's and a fantastic Falling Block works in 30-40 Krag AI. I have kinda been adding the various tipe of Snider's lately. Recently I obtained a Snider "Trade" Conversion. I have not been able to ID the custom modification to this action. I am attaching 20 + pics for your assistance.  I have had the oppertunity to discuss this beautiful rifle with Mr. Ian Skennerton and he also just confirs it is a top line conversion and more research to find thebuilder.  The bottem of the barrel has the "TT" marks for the builder Thomas Turner and a very faint name that appears to be Henry or Henri  Oliv--. The caliber is standard 577 Snider. Thanks much. wsmrto