Mine became a flamethrower—when it broke! It might have been because I carelessly left it on the floor and some debris fell into one of the air vents when I wasn't looking. I turned it on and pop! A small fireball went out and the temperature gauge shot up past the stated maximum on the box.
It was pretty cool while it lasted, though. Here it is:
https://www.amazon.com/gp/product/B0106JNHMW/
Independently adjustable air temperature and air flow, along with that super useful digital temperature gauge (without it I would not have known it was getting dangerously hot, there might have been an even bigger explosion). These days an ordinary hair dryer works fine for me but I'll need a heat gun again to debind the stronger higher quality mags like Next Generation and the old Macworlds.
Anyway, do not leave your heat gun on the floor.
As for my method, I try to take the whole cover piece off first. That leaves the inner pages bound by a solid strip of glue. I let the glue side hang off the side of a box or whatever and then start removing the pages. If successful, then the last page will have a big honking strip of glue on it that I can just pull cleanly off as one solid piece. Worst case scenario the glue melts too much and gets goo over every page. That's why I figure it helps to err on a lower temperature, if you're not sure what temperature is appropriate.
500°C seems very high. Doesn't the glue get all gooey for you?