Help! Tips on greasing the upper ball joint?

[TheRealPoser]

Hi folks, I just installed some Nitro UPCs, and I'm getting stumped on greasing the ball joints. The UPCs come with no instructions at all except for a note saying the ball joints are not pre-lubed and they must be lubed. They've got zerks so no biggie I think to myself.

Well, now I'm trying to grease them up and I can't get them to take any grease. I get the grease gun snapped on there nice and tight, tight enough that the first time I couldn't get it off without unscrewing the tip to relax the grip on the zerk head. Every time I try to add grease it just oozes out around the zerk head and makes a mess. These are brand new UPCs and ball joints.

In searching around the interwebs I've found all the following ideas, none of which have made any difference whatsoever:

• Removed the zerk, verified I'm getting a free flow of grease through the zerk, so the zerk is not clogged and the little check ball is not stuck
• Unscrewed the zerk half way. Some people claim if the zerk threads are too long they can somehow bottom out inside the ball joint and prevent grease from flowing. All this result in is grease oozing up around the threads instead.
• Greasing with the weight of the LC resting on the wheel, and jacked up with the UPC at full extension down
• Greasing with the wheel turned full left, full right, and centered
• Prying up gently on the bottom of the boot with a plastic shim to break the seal between the knuckle and boot to let air escape while greasing
• Greasing while patting my head and rubbing my belly and balancing on one foot

To make matters more confusing, one person on a jeep forum stated they spoke with the manufacturer of another brand UPC and were told the boot would not inflate with grease and the joint only took half a pump of grease. If that's true there is basically no way to to tell if the joint has sufficient grease. I've seen other 'how to' instructions saying to pump until the boot starts to inflate and then stop so as to not over fill. I have looked closely and the boot hasn't moved one iota, and it feels empty still.

Every pump on the grease gun has just ended up with a greasy mess around the zerk. I'm fairly confident I haven't gotten even half a pump of grease to actually go into the joint. I'm out of ideas. But I also don't want to just drive on it an hope for the best, as if it fails early it will just be my fault for not properly greasing! I've reached out to Nitro but haven't received any response. Any ideas??