Your question relates to expungement. Unfortunately, it is nearly impossible to expunge a criminal conviction in Pennsylvania unless you meet two very important criteria. You must be at least 70 years of age and you must be free from arrest/incarceration for a period of 10 years. Assuming you do not meet this criteria, you will not be able to have your record expunged.
You should consult with and retain an attorney to advise you on gun ownership. You could also explore a governor's pardon if you have sufficient reasons.