Gun Control & RKBA

They block the hammer until the trigger is pulled, make it safe to carry with all the chambers full.

A derringer with an empty chamber under the hammer is an unloaded derringer: not exactly a useful self-defense tool. Derringers have seen their day, in any case. Technology has progressed to the point where semi-auto pocket pistols holding six or seven rounds are barely larger than derringers, and are much safer and more reliable.

Then there are the NAA mini-revolvers, which hold five rounds and let the hammer ride safely in a notch between cylinders.



In short, there is no reason to carry the traditional two-shot over/under derringer unless you're heavily into Old West cosplay.