I was a Hatfield dealer for about ten years when they were still operating out St Joseph's MO.
When the orders got piling up, and Ted couldn't get guaranteed deliveries on barrels and locks, he went to
Pedersoli for everything except the wood. Ironically enough, Hatfield's brochure was titled, "Uniquely American".
We tried switching barrels one time, and that's when I saw the Italian proof marks on the bottom flat.
I called Oz at Log Cabin Sport Shop to tell him about our find. A number of barrels had the proof marks & name filed off.
If one is going to remove the breechplug, one must first remove the vent liner, otherwise you will shear off half of the vent liner. Don't ask me how I know that.
I always thought the lock size was out of proportion to size of the stock. Fouling will continue to build in the ante chamber of the breech, so one must use a .22 caliber bore brush to clean out the carbon. Since the Blue Ridge Hunter by Pedersoli is the "Italian Hatfield", it will have the same difficulties as Ted's Hatfield.
When Jack Garner began offering his TVM rifle models, we switched horses in the early '90's (?) and never looked back. When Matt Avance took over TVM, the rifles continued to exude the All-American" quality that started with Jack. When I saw Matt at Fort Fred, I'd come away with at least a half-dozen pieces.
Good luck with what you have. Just keep a .22 cal brush handy to put on your range rod every 10-15 shots.