What really makes me really squirm is snapcaps in a hammergun case!
Forgive my lack of knowledge on something that is probably clear to others here, but why?
It's because there is no need to dry fire a hammergun to uncock the hammers. You simply hold back the hammer ear, then pull the trigger to disengage the sear, and slowly let the hammer down. You can do this one hammer at a time, or both at once if dexterous enough. Of course, great caution must be exercised if you uncock the hammers with live shells in the chambers, such as while hunting. If the hammer slips from under your thumb, it can fall with enough force to fire the gun.
There are also some hammerless doubles that can be uncocked without dry firing or utilizing snap caps, such as the Syracuse Lefever. You simply hold the gun fully opened to put tension on the cocking lever, pull both triggers as you move the safety to off position, and close the gun. The internal hammers are gently lowered without any risk of dry firing damage to the firing pins, and the mainspring tension is released.
