I just have to ask, how the heck do you get six cans at half off?!?
I got them from some local matches. Since Silencerco is in Utah, they sponsor a lot of matches. I got one card for being an RO at the Quiet Riot this past summer. Each card entitles you to 3 cans at 50% off. However all 3 cans have to be purchased at the same time. I got another card from my buddy that was an RO at the Quiet Riot in 2015. They actually gave him 2 of them and he passed one on to me.
Locally, guys sell their pro-deal cards for about $600 a piece since it has the potential to save you lots depending on the cans you buy. Me, I'm just saving them since I currently have 6 cans. I think my next purchases will be another Omega 7.62 and then 2 of the Omega 9k silencers. I'm also contemplating picking up another Sparrow but I got to see and use a Thunderbeast 22 Takedown and it seemed a little nicer than the Sparrow and it also cost less.
Sooo, random question, but where is one likely to keep said cards..? In a particular desk drawer or..? 
So, right now one card is in the safe and the other is in my email somewhere as they send the cards for the 2016 Quiet Riot as an electronic link. Good luck hacking.