Figured I would post this to see if anyone else is having the same issue. sometimes I will get 100 xp for a kill when I should be getting 150 (this is ignoreing addtional bonuses like headshots and killstreaks). At first I thought it could of been a UI bug but I checked my xp to next lvl each time untill I got a 100xp kill and it seems to be missing the extra 50. Been happening pretty much since I subbed but I never really put much thought into it thought I would check here to see if this is intended or not before I open a ticket.
I believe we had an extensive discussion about this a few days ago - I think the conclusion was that it DOES apply as intended, but it doesn't display it correctly on screen always.