The fine folks behind the IJC weapons pack are working on some brand new weapons. But in order to get one of them unlocked, 1000 Likes are needed on their new IJC Facebook page. So head on over and give it a like (and make sure your friends do as well!), and don't forget to vote for your weapon of choice on their forums.
Also as a reminder, you can also follow Tripwire through various social media as well! Twitter, Facebook, and Youtube. I'd mention our various Official Game Groups on steam, but I figure you already know how to find and use those!