I have fired a lot of big bore handgun calibers including: 375JDJ, 50A&E, 500 S&W, a bunch of rifle caliber contenders, encores, bolt action pistols, etc. but the most painful hand gun I ever fired was a full house 45/70 load in a 2 shot derringer. My hand hurt for a week. When the owner of the custom made pistol fired it, the pistol flew out of his hands and hit the back wall of the silhouette range. The grip panel broke off. I never saw him fire that derringer again.