Ever since I updated my xbox (had to update it in order to play Halo4), not only did I loose all my achievements for halo reach and halo 3, but something seems to have happened to the exp rates for my reach. No matter what I do, I only get 50 exp each time.
I played a firefight where I got 1kkk points (for the achievement), the 8th mission, start to finish on legendary, and about 10 mins on the 2nd mission, they all gave me the same exp, namely 50… So maybe it’s just me, but it kinda feels like something’s wrong with that?
That sounds exactly like what happened to me when I had to update my xbox and first took it online to link my REACH service record with HALO WAYPOINT. It reset my Rank to 0 and took all of my points. Ever since then I only get 50pts per game if I play FF privately offline. You should still be able to get better points playing Fire Fight MM online but you don’t get to choose all of the settings there like you do offline.
Hope this helps.