In PA, the only caliber limitation for centerfire firearms is .27cal or higher for elk. For deer and black bear you may use "manually operated centerfire rifles, handguns and shotguns with all lead bullet or ball, or a bullet designed to expand on impact." We used to have a .24cal mimimum for deer, but it appears they dropped that restriction. There are minimum caliber/equipment requirements for muzzleloader, flintlock and archery hunting though. Always good to check though, as they do change the regs periodically!
BPL
BPL