I have a couple of Chicago Pneumatic 717 guns that I have had for 20 years or more. They use a .498 shank chisel. They are expensive new. Occasionally they appear on eBay or at pawn shops. A 5x Rivet gun is about the same as a large air chisel, only much more controllable. However for occasional work, I don't think you can cost justify a heavy gun. I would just grind the button flush, apply a little heat, and give it a good pop with a drift punch.
