How do I use the Tactical Enhancement pack I redeemed in Deus Ex?
Solution 1:
According to this thread the bonus is added right after your brief with Sarif on the flight to the manufacturing plant mission. If you activated the code after that point, then you will not receive the bonus.
Solution 2:
The new weapons also show up at the regular gun vendors. I'm not sure which vendors get which weapons, but I found both the Silenced Sniper Rifle and the Double Barrel Shotgun at different vendors in China.