There used to be a guy named Tom Ondrus who was once a fixture at Pa. Gun Collectors Assn. shows. He was also a somewhat controversial member here at one time. He sold and displayed a lot of Double Rifles built on shotgun actions, and also sold investment cast and semi-finished parts to guys who wished to build Double Rifles.
I responded to an ad he ran in Shotgun News, and travelled to his tool sales business in Austinburg, Ohio to buy a Wickliffe single shot rifle from him. We visited for a couple hours, and he showed me a very large inventory of various parts for double rifles including barrels, ribs, express sights, buttplates, grip caps, etc. He also had bought up almost all of the unfinished actions from the Wickliffe 76 Rifle Co. that had gone out of business. He had a heat treating company doing the heat treating, and had a gunsmith who was threading, chambering, and installing barrels for him. And he also shared a lot of the information he had acquired about the Wickliffe Rifle Co. He showed me one particularly beautiful 20 bore Double Rifle, just regulated and nearly completed, that was built on a Simson shotgun action as I recall. The wood was gorgeous, and the workmanship was flawless, similar to what we used to see from Dewey Vicknair.
He was an interesting guy and an entrepreneur. He hunted Africa several times and had a lot of trophies and stories.
A few years later, his health declined and he still came to the PGCA shows in a wheelchair, and then passed away shortly thereafter. His tables at the PGCA show were always busy with guys buying and bringing in partially completed guns to ask him questions about. I never heard what ever became of his considerable collection of finished and unfinished Double Rifles, Wickliffe single shots, and enough parts to fill a couple pick-up trucks. Unfortunately, I never thought to ask him where he bought all of the parts he sold to Double Rifle builders.