Whoops, I must have misread the law. Re-reading it, the relevant laws are:
Sec. 2308. Unlawful devices and methods.
(a) General rule. - Except as otherwise provided in this title, it is unlawful for any person to hunt or aid, abet, assist or conspire to hunt any game or wildlife through the use of:
(1) An automatic firearm or similar device.
(2) A semiautomatic rifle or pistol.
(3) Reserved.
(4) A semiautomatic shotgun or magazine shotgun for hunting or taking small game, furbearers, turkey or unprotected birds unless the shotgun is plugged to a two-shell capacity in the magazine.
(5) Any device operated by air, chemical or gas cylinder by which a projectile of any size or kind can be discharged or propelled.
Sec. 2322. Prohibited devices and methods.
(a) General rule. - Except as otherwise provided in this title or commission regulation, no person shall hunt, kill or take or attempt, aid, abet, assist or conspire to hunt, kill or take any big game, except wild turkey, with any of the following devices or methods:
(1) Any device other than a centerfire or muzzle-loading firearm or bow and arrow.
(2) Any automatic or semiautomatic firearm, except that any semiautomatic firearm modified to permit one shell in the chamber and no more than four shells in a magazine may be used by a person who suffered an amputation or lost the total use of one or both hands.
(3) Any firearm propelling more than one projectile per discharge.
(4) Any projectile which is not all lead or which is not designed to expand on contact.
(5) When any big game is swimming.
(6) By any other method or device which is not specifically authorized or permitted by this title or commission regulation.
(b) Penalty. - A violation of this section is a summary offense of the fifth degree.
(c) Contraband. - Any big game killed contrary to this section is contraband.
PA laws are crazy. No caliber or barrel length restrictions, just gotta use a centerfire with all lead or expanding bullets. So hardcast lead bullets are legal, Punch Bullets are not. A 5.5mm Velo Dog revolver is legal, yet a .50 caliber Quackenbush airgun is not. A bolt gun in .10 Eichelberger (yes, .10) is legal, but a BAR (one of the new ones) is not. Crazy.