If you are on Facebook, the primary group to sell at would be Longarms and Accessories for Sale. It is a private group (which keeps the scammers and spammers down). You can also try the regular portion of FB Marketplace, especially since you are likely not offering shipping.
That said, watch for scammers, even on FB. Check the profile of a person inquiring and make sure they are local and have some history. I had someone who, after a few messages, was clearly a spoofed account based on their strange questions.
Craigslist used to be an option, but there are horrendous scammers there these days. Do not, under any circumstances, agree to bank check (those can be faked), especially from someone who doesn't want to personally view the item and is having "a friend" pick it up.