I have had my Cowboy Defender (45LG/410) for a couple of years now, I carried it a lot when I first picked it up. I took it out and patterened it with 45acp. Hornady Gritical Defense, 410 Rifled Slug, 410 Buckshot, 410 PDX and 410 #6 shot at twenty-one feet.
In my Cowboy Defender it had the best pattern with the 410 Buckshot and still has two rounds setting in the barrels. Abot all it's good for is a close up self-protection handgun. I'll probably just keep it and occasionally carry it every once in a while. A friend bought the Texas Ranger model in 45LC/410 and loves it, he have several handgunsand prefers to carry his Bond. He bought the 38spl/357mag barrels, the 9mm barrels and the 22lr barrels for it.
Bond carry a full line of extra barrels in a huge variety of calibers, all of the barrels are interchangable with all of the different styles of recievers. They are the best built Derringers out there at a very affordable price plus the option of almost any caliber barrel you might want for your gun.
For a truck or car gun they are GREAT, or to throw in your pocket to run down to McDonalds or the corner store.