I didn't find out until level 54 when I read it in this forum. Don't matter tho, grenade launcher sucks. There are only a few people I've seen who were decent with it. Otherwise, I love watching these guys runnin around kamikaze style. Having Last Act of Defiance gets them almost every time as long as they're fairly close.
I hate grenade launcher, unlocked it used it for a day and put it in the tool shed. What I really hate about grenade users is they can ruin a good kill streak with no talent
someone had 29 kills and 1 death and was eliminating my team, thought i'd break it out and end it, hunted him for the rest of the round, got a fair few kills on him with it