IR ThunderGun Impact Wrenches any opinions?

So how do you guys go about lubing your thunder guns and what type of grease do you use? I am less than impressed by the instructions that came with mine. Its just a drawing of the gun with a picture of a grease gun pointing at the front and pointing at the back. I see what looks like a euro push pump type of grease fitting on the back but I have no clue what the hell they want you to grease on the front of it. Any ideas on this situation?