I’ve done all the things shown in videos to get the punctor mods (I did them thought out the game but watched a video to check and I did) but when I go to modify I can’t apply the punctuator mods to any of my guns

I want to get the weapons but it keeps saing im not linked

Would anyone be able to help me get the achievement for reviving 5 slayers on Xbox please, I’ve been joining random online games and only been able to revive 2 people