I usually just use a punch that's the same diameter. May take a little persuasion but I've not horribly damaged any yet. That being said I'm not an expert and have no clue if there's a better method. I've done gas block swaps 6 times so far

 

Got the pins out. Ever had a stuck gas block? I’ve hammered the **** out of it. Not moving an inch

 

Maybe spray them with a little Kroil? That stuff is the penetrating oil’s penetrating oil.

 

Actually got them out. But this gas block is not budging at all

 

Remove from left to right. Replace in reverse

 

Heat the gas block up then tap off with a piece of wood...............

 

 

Maybe hit it with your purse?

Kidding, I use a press sometimes to push the gas block off. Using an old flash hider to protect the threads.