Below is a diagram of the rear base on a snap-action drilling I acquired last week. I have never seen this type base before. I am guessing the latching mechanism is in the ring. NECG responded immediately to my inquiry but don't have the ring or know where to get one. I have fabricated rings for claw mounts before but I need something to go by.

Does anyone have a picture of the ring type or can point me towards one?

Thanks,