cletis911
Use your thumb to press lightly on the barrel hood where it locks into the ejection port as you pull the slide forwards. This ensure that the barrel won't attempt to unlock, adding further tension to the slide...
Sounds like that your hammer is pushing against the slide pretty hard, and is possibly creating undue friction between the slide and frame rails. Make sure (!) the mag's not in the pistol, and look up into the grip at the bottom of the slide. It's possible the guide rod has slipped from it's position on the barrel lug and is riding under the barrel, tying things up... not very likely, though. If it is, use a small screwdriver to push it back forwards to the front of the pistol.
Assuming everything looks okay, you're going to have to simply use brute force to pull off the slide! Some P-3ATs are simply hard to pull apart... sometimes you've gotta be rough with them!
Flyer