First I suggest you contact the chief law enforcement officer with the PA Game Commission via letter and include a copy of the photos/drawings of the various types of German firearms. Address your desire to use a drilling or other combination gun legally in PA but indicate your concerns.
We did the same thing in Ohio two years ago and found that the Ohio Division of Wildlife chief law enforcement officer agreed that there was no problem using a combination firearm for hunting deer, etc. as long as only the correct ammo legal for what was being hunted was carried. He then sent a communication to each Supervisor at the five Wildlife District offices and ask them to communicate with all of their game protectors that a combination gun was legal to hunt with as long as the ammunition carried was allowed for the game hunted. Prior to this some of the field officers did not believe it was legal to hunt with a drilling, etc.
Ohio does not allow bottle neck cartridges for deer hunting however after some campaigning by many sportsmen, Ohio agreed to allow an expanded list of straight wall cartridges for deer hunting. Now straight walled rifle cartridges are legal to use from a minimum of .357 to a maximum of .50.
You are correct that using a combination firearm for small game and deer at the same time may not be legal in some states.
Ohio does not allow small game hunting during the regular firearm deer season- first week. It is legal to hunt feather or fur with a combination gun during the open small game season here. The only exceptions are wild turkeys and waterfowl cannot be hunted with a rifle.
I had a Merkel over/under 16 bore/ 9.3X 72R that I hoped to hunt deer with last year. It was legal to carry and use. I used the Merkel with both a slug in 16 bore and rifle ammo for 9.3X72R. It was a successful hunt with a great memory!
Communicate with the game department and encourage others to do the same if they have a desire to use a combination firearm for hunting in your state.
I wish Ohio would allow the use of bottle neck cartridges for deer hunting.
Someday- maybe??
Good Luck!
Jim

Last edited by ohiochuck; 11/11/18 10:18 PM.