Howdy
What you probably have there is a replica of the Sharps rifle made by Pedersoli and imported by EMF. It is not a Quigley model, Quigley models are based on the fictitious gun used by Tom Selleck in the movie Quigley Down Under. Generally speaking, a Quigley model will have fancier wood, a patch box on the right side of the butt, and a pewter forearm cap. If anything, it most closely resembles the Sharps Business Rifle. This was the name the actual Sharps company used to describe their basic rifle in the 19th Century. This link will take you to the Sharps rifles imported by EMF. Notice the one called the Down Under Sporting Model. That is a Quigley Model.
http://www.emf-company.com/store/pc/...rsoli-c451.htm
This link will take you to the Pedersoli Sharps Business Rifle imported by Dixie Gunworks. Notice the double set triggers, and plain wooden forearm. The only real difference between your rifle and these is yours has checkering on the wrist of the butt and forearm. But I still think it is a Pedersoli Sharps Business Rifle.
http://www.dixiegunworks.com/product...oducts_id=3469
Gardone is a firearm manufacturing area in Italy, and several firearm manufacturers are based there, including Pedersoli, Beretta, and Uberti. Since that is a modern firearm produced with modern steels, it is not limited to Black Powder, it can be fired with smokeless 45-70 ammunition that meets current SAAMI standards.