If my memory of PA game laws is correct, you could probably be OK hunting during deer season with a drilling because coyotes are also open at that time. If you carried a box of the "Dead Coyote" shells for the shotgun, you'd probably be ok. Similarly, slug loads and rifle ammunition would be an OK combo as both are legal for deer.
The problem with that, besides a thick-headed WCO (game warden) would be that saying "I don't have any birdshot on me" would invite a body search so the warden could "make sure".
Thing is, during deer season you probably couldn't carry buckshot for the coyotes because as I recall is buckshot is illegal for use on deer in PA (except, possibly, some of the more suburban counties).
Similarly, you could probably carry rifle ammunition as well as birdshot during the small game season prior to deer season (like, now) so long as bear was open and you had a bear permit. Actually, hunting bear with slugs in the drilling would be a good match, especially if you were one of the standers on a drive. Sorta like being a stander for wild boar.
After deer season closed, though, you'd probably have to leave the rifle ammo home, though you might be able to weasel through with the coyote hunting thing.
For me in Maine, the drilling is the "perfect" November gun, because all small game and deer are open this month. I can load two birdshot and one rifle and be good to go. OTOH, when on a moose hunt (if not a permittee or subpermittee) the best policy is to leave anything with a rifled barrel home. The permittee and subpermittee are the only people who really can legally have a rifle.
