I will add my 2 cents on the .221 FB as well, since others have mentioned it. I have an XP-100, all original except the Fajen stock, that is chambered in .221 FB. It's just scary accurate for a pistol and is an absolute dream to shoot. Hardly any recoil, really easy on brass, is capable of very respectable accuracy, very respectable velocity even in my short barrel (10.75"), brass is available or easily formed from .222, .223, .204R, etc., and the best part of all, it uses a standard .223 diameter bolt face and can be chambered very easily in any short action with a .378 diameter bolt face. So no special machining or oversized rimfire actions necessary, no rimmed brass, better and thicker brass than the hornet, the benefits just go on and on. Really just an awesome little round, and my second favorite .224 caliber round, after the .222.
The .221 FireBall is also the parent to several other excellent rounds that should also be of consideration, the .20 VarTarg and .17 Mach4, and is also parent to the .300 Whisper, 6mm Whisper, 6.5mm Whisper, 7mm Whisper and the .338 Whisper #2 (the .338 Whisper #1 uses 6BR brass). With the great ballistics of the .20cal bullets, the .20 VarTarg is a very attractive option, as .20cal bullets will usually have a higher BC than a .224 bullet of the same weight.
If you do like the Savage Lightweight Varminter, you may also want to look at the 5.7FN offering, as it produces ballistics similar to or slightly better than the Hornet and uses stronger brass from what I understand. I was going to buy one for a short range small game rifle, but as I stated earlier, didn't really like the rifle all that much. That is only personal preference though.
Kenny