The single pin lockup exactly on a radius of the hinge pin should be quite strong but it poses a couple issues which immediately come to mind.
First, a round pin on radius offers no resistance to rotational forces at all so I would suspect that wear on the hinge could be increased although the lump helps in this too.

Secondly, there better be a sear or block to the sprung pin so it doesn't want to open under recoil.
And, the open spaces in front of the hammers give access to the internals of the action for all sorts of stuff to get in.