> Thanks for the response, I thought this was going to be the answer.
> Will MAME automatically not use the light gun flash if possible? Or will the be a
> setting somewhere to turn it off or on?
Not sure what you're asking now. Turning it off would literally involve hacking the game code on a per-game basis, and on some games (the NES baesd ones for example) would actually break the game, because the game code specifically looks for white pixels when you fire the gun.
This is out of the scope of MAME.
If you're using an actual light gun on a PC it will have it's own way of detecting things and might even introduce it's own flash.
Luckily? most arcade games didn't use real lightguns, so didn't have a flash anyway.