Welcome to the forums from the Wiregrass! I know you are new so I have a couple of comments to help you along. First, you posted in the wrong forum. There is a Classifieds forum where you can sell your M27. Expect this post to get moved by the mods/admins. Second, you won't sell anything without sharp and well lighted pictures. Lots of pictures. Particularly when selling a NIB handgun. Third, this isn't an auction site so don't ask for bids. Research your gun's value and set a price before posting. For reference, go to gunbroker.com, create an account and then read the COMPLETED auctions in the advanced search feature. Hope that helps!
I've only been a member since 2012 so can't say when the rules may have changed before that. To my knowledge, there never has been a required number of posts to post a for sale ad. Here are the rules. You must be thinking of another S&W site.