Sometimes carry a Davis D-38 in .38 Special. Favorite ammo is Strike Three. I'm convinced that this stuff was made for derringers. It packs three .30 caliber buckshot balls into a one of Speers plastic shotshell housings. I also developed a home-brew load for the same. Instead of three lead balls, use slingshot ammo and put four STEEL balls at .25 caliber, plus you can squeeze a fair amount (more than a .22LR shotshell) of #12 birdshot into the case with it. Devastating at close range to snakes, varmints, and most medium size critters. I wouldn't recommend it for bear, but it should be effective against two legged varmints (at close range).