Yup, timestamps usually work out best so there are no misunderstandings. It's hard with gunbroker because once it is bid on, even if by an F rated buyer you know has no intention of following through on the deal, that auction is stuck until you manage to end it or the time expires and you clean up the mess afterwards (hopefully not having to fight too much to get the listing fees refunded).
I'll be very interested to see what you have in the pipeline. I'm sad to see you letting go of so many nice ones, but I understand that life happens and sometimes what you bought 5 or 10 years ago doesn't fit your lifestyle today.