Grouse, you asked a question regarding the requirement to use expending bullets in muzzle loading seasons in PA. This is the law regarding that, it is the law for big game season regardless of the firearm.

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.

I hope this answers your question.