Earlier was question of barrel thickness. I had it at the smith's yesterday and 10" from muzzle the 12 ga. barrels show min 23 thou on one side, 25 on the other. The 10 gauge: 32 and 38. I will leave the gun with him for a more thorough evaluation before I fire it. There is a small amount of play in the action and possibly the design allows a slight adjustment to the cam to improve the lockup. Will see.
As to which was first, the Fox swing opener or Jefferies, I really have no info on that. They would both date from same period.
