Drive to AZ or NV. He’ll, I might set up an ammo and hot dog stand at the border.
Actually, there's already similar near CA/NV involving fireworks this time of year. Being as almost all of Kalifornia outlaws 'em.
Riverside and San Bernardino county "undercovers" have been known to lurk and do stops once back in CA.
Pennsylvania has alcohol sales being a state operation. People tend to buy their wine and whiskey across the border. PA has people recording license plates of people who parked at NJ and Delaware liquor stores just across the river from Philadelphia, and would stop them at the toll booth, inspect their cars, and fine them.
I would imagine California would be even more draconian with respect to out-of-state ammo purchases.
You would need to park a couple of blocks away and pay cash.