That add on will soon disappear. Why? Because I've looked around on-line and tier tactical 1 is getting really uncommon around here and T+T2 edits or removes allot of the weapons that you might have liked in T+T1. So what i would recommend to do is make a backup file in your computer and save them there. (The file could contain add ons that don't work well together. So you could make an add on collection of hundreds of add ons to give to new players who need them.)
Your welcome for saving you from hours of searching! :D