Should I go to trial if I’m being charged with possession of a firearm that was found in a backpack that I was carrying?

In response to your question, Should you go to trial for a charge of "Possession of a Firearm that was found in a backpack that you were carrying" I would need far more information to respond to that question. It is not something that should be discussed with anyone but the attorney representing you n the charges. Information on the circumstances which led to the stop & search are critical. Also what your previous criminal history looks like and the specific chapter and section that you were charged under.