theres nothing in the penal law about accesory…
theres a couple charges for facilitation but you have to do something knowing the person youre helping is going to commit a crime. Selling a rifle to a person of poor moral character that you aren’t sure would pass at a store backround isn’t faciliatation. It doesn’t meet criteria for criminal liability. I’m sure there are charges for selling to someone who you know is a felon though I don’t know what they are.
prolly just criminal purchase.