I have been told that you can't hunt with a semi-auto rifle in PA to include varmit hunting. Is it possible to hunt with an AR-15 if you only carry 1 mag that has been plugged to allow it to hold no rounds. This would allow you to single load only.

well the way i read the rules it would be no. i believe they state that the rifle or handgun must be manually operated.

It is still a semi-automatic, isn't it?

George

GBTX01:

"Unlawful Firearms and Devices1) Automatic and semiautomatic (autoloading) rifles and handguns; (2) air or gas operated rifles and shotguns."

From Pg. 10, "General Hunting Regulations", Pa. Digest of Hunting and Trapping Regulations

In my experience, the Game Protectors / Wardens are quite literal minded in interpretation of the laws and regulations, are very free in issuing violations, and enjoy state-wide ~90% conviction rates. If so cited,You could challenge it in court and make the assertion that you "manually" loaded the single round using the T-handle. Not being a lawyer, I couldn't guess the percentages on this ploy, but I wouldn't gamble on it.
Enjoy,
Rosse