To my knowledge which is faulty at best, the founders of the two firms mentioned were indeed related. Cousins or brothers or some such. Quality of both is renouned, though I have only dealt personaly with the LaFayette firm here in NY. My personal .308 Sako is on the cover of their brochure along with my best whitetail. A tremendously accurate rifle. I would strongly recomend their work.
One Hart (Clyde Hart and, later, his son P.J.)was the barrel maker. The other, R.W. Hart was the action maker and seller of BR equipment. I believe there is a family relationship but don't remember what it is. The actions are no longer being produced (to my knowledge) but they are still building rifles and selling accuracy related equipment. Regards, Bill.
I used to live about 20 miles from the NY Hart barrel-maker's place. My hunting buddy does business there all the time. Yes, there is a relationship between the two Harts of the NY and PA businesses. I may be wrong, but I believe it is uncle (NY)/nephew(PA).
The NY Hart outfit does OUTSTANDING work. I have never seen any of the work from the PA Hart outfit.