i use synthetic oil for my guns too.
ATF fluid is flamable at relatively low temps. not a good thing to be using a gun that produces heat. had a old truck of mine catch fire because of a ATF overflow that dripped on the catalytic converter. was a chevy manufacture error that they didnt include a discharge tube.
anyway if you run a gun hot enough ATF will catch fire. synthetic oil wont. plus ATF has very little lubrication properties.
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." — L. Neil Smith
The problem with being stupid is you cannot simply decide to stop doing dumb things...
"I crapped my pants to avoid the draft!!" -Ted Nugent