need help field striping AR-10

AHHGG!. I just got my Armalite Ar-10 home. I was following the instuctions on field stripping. I have run into a problem. I cant remove the fire pin retaining pin.....it WILL not come out. Is there some trick to this or do I need a gunsmith? Please let me know....this is my first AR type rifle and I am hoping I that I don't have to ship it off before I even get to fire it.

Thanks for your help