Hm... The 9th Circus court seems to think MJ might impair someone:
In Pennsylvania, state police told Lehigh Valley Live that using medical marijuana automatically disqualifies someone in the background check process from buying a gun.
That lines up with a 2016 ruling from the 9th Circuit U.S. Court of Appeals that said it isn’t an infringement of someone’s Second Amendment rights to ban them from buying a gun if they use weed.
“It is beyond dispute that illegal drug users, including marijuana users, are likely as a consequence of that use to experience altered or impaired mental states that affect their judgment and that can lead to irrational or unpredictable behavior,” the court said.
So what do you pot heads think? I have never used any MJ, and I don't have any first hand experience to base a judgement on. I have seen plenty of people under its influence, but that is not the same.