Dude,
Pabst and
good never belong in the same sentence without a negative modifier... :barf:
Seriously though, beating on it only does so much. Using the 4' pipe was a good start, but you really need something longer. My buddy has a ten foot long pipe that fits a breaker bar nice and well for those ridiculously stuck bolts. I suggest finding the same. Forgo the hammer, just apply massive amounts of torque with a long pole... And get a few buddies to help...
The only other thing I can think of is rigging the barreled action upside down and using a hydraulic press on the bolt handle...