If that nut is threaded onto the center shaft, you're wasting your time hammering on it. No thrust whatsoever is being applied to the wheel hub. You're just trying to yank the shaft out of the steering gear. If the thrust is applied to just the puller in some way, you're fighting a tapered spline which is extremely unlikely to come loose by hammering on it. The way it's been done for decades, with a slotted foot on the puller, works.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!