Just for clarity. You did remove the gas cylinder plug and gas cylinder lock? If these are removed you are going to have to tap it off with a hammer. Use a block of wood or aluminum directly on the gas cylinder and a small ball peen hammer. Rubber hammers don't work well for this sort of thing. You need a solid blow, but don't hit the gas cylinder directley with the hammer.In the link that I sent, what step are you on?
I may be wrong here, but I don't believe DAG is corrosive, just berdan primed. Good luck anyways, though.It was bought new in the box - SA. I suspect it was the DAG surplus ammo I recently gave away. It was the dirtiest ammo I ever shot...and corrosive. Anyway, it is soaking in Kroil and I will try removal again in the morning.