Parkers in the Remington Museum

[B. Dudley]

Well, the Charles King designed Hammerless guns uses the Bellcrank mechanism to cock the guns. With all that there, there is no room for a check hook and pin as used on the hammer guns.
The hammerless design used the milled cut in the frame for the cocking crank as the positive stop for the barrels.

I still cannot figure fully why Hayes used a separate piece in the barrel lug for the check hook on his second prototyle instead of an intigrated hook like the hammer guns. I would suspect as to make the hook replacable in the event of breakage. But I do not know of check hook breakage being a common issue on hammer guns.