Your gun is an extremely nice example of a post-1913 Field Grade (post-13 guns have the grade designation roll-stamped atop the barrels) special ordered with an English style straight grip stock and optional auto-ejectors (straight grips are not common on Field Grade models). Your gun also appears to have English walnut stocks, also an unusual feature of post-13 Field Grade guns which typically feature black walnut stock wood. The gun was built by Hunter using their standard, or "R" (regular sized) gun frame; as opposed to their smaller "FW" or feather weight frame. I've no idea if the rubber pad is original to the gun or not; but your gun appears to be very shootable, and I wish you years of shooting enjoyment. Best regards, Tom
PS - a research letter may contain additional information and I suggest you order one, as having that document only increases the value of your gun.