I used to duct tape the handle down, put on some goggles and hearing protection, wedge myself in between the fire pump and seawater service pump in the auxiliary engine room, and go to sleep for about 2 hours needle gunning the same 6in square on the base of one of the pumps...
Probably took off more metal than paint after awhile.
I could only sleep for 2 hours because by then the water would have risen in the bilge to start washing my rear!
I must have pulled that stunt for about a week. Whenever someone came up, they had to yell to get my attention, and of course that would wake me up. Ah, those were the days...
Super tool for removing rust, paint and scale. Ditto on the using it on thicker metal.