A 22 K-Hornet barrel is another nice option in a Contender, especially if by handgun you mean a 10"-12" barrell instead of a 14" handrifle. The K-Hornet chamber will handle regular 22 Hornet rounds. After you shoot them, you will have a ready supply of blown out K-Hornet cases to reload if you want a little more zing than the regular 22 Hornet. The K-Hornet is kinder on stretching the cases than a regular 22 Hornet too. There are faster and longer range 22 choices (223 for example), but in a pistol? The big step up is from 22LR to something that can shoot pointed boat tail bullets. After that, it comes down to how much blast you want for an incremental increase in range.