Can you use caliber larger than .224 for varmints? If yes a 243 would do the work of both varmint and deer hunting. If the father doesn't reload stick with cartridges you can buy almost anywhere.
I've used .22LR, .223, .22-250. .257 Roberts, 7mm RM, .375 Win, .44 Mag and probably others for prairie dogs, coyotes and other varmints. The benefit of a .223 is cheap ammo, especially for those that don't handload.
