When I was starting into gear for the first time, there was a law then (in my state) that if you bought a certain amount of syringes, they could check on them. Police would come out and ask you what they were being used for and ask to see how many you had. I assume it was a scare tactic but they did a checkup on my aunt after she purchased a bunch for her daughters allergy shots.
Anyway... I wasnt going to be doing that so I would buy them at the feed store a few at a time. Nice huge fullsized cow needles... My first injection half the test shot right back out the enormous pin hole.
Thank God I dont have to do that again.