I am not 100% sure on this, but from the looks of the replay and from my point of view in-game, it appears as though Jeanpperry is using a hack that dismisses the damage of ranged weapons only. This means he can only be damaged by melee weapons and possibly other things. Of course, since GunZ replays are strange, my shots don't register properly because I was reload-shooting. I assure you that at least 85% of my shots hit him from point-blank range. Another pair of eyes would be helpful for this, so here is a replay file for anyone who wants to verify:
http://www.mediafire.com/?wrcn7ngnmw9n1s3
