Private vs Commercial Sales
If you own something and want to sell it, that is a private sale.
If you bought something in quantity and are now selling it for big profit because the demand is ridiculous right now, you are most likely a vendor. We may take some excuses and exceptions to this, but it is completely at the judgment of the moderating staff. It doesn't matter if you think you are a business, it becomes a business transaction.
This is not a policy to restrict or harass the members from selling off their private goods, this is a policy to protect the investment that the actual vendors on Calguns have made to be able to advertise here. It's usually such small quantities that it doesn't really matter, but I'm starting to see people take advantage of both the situation and the website.