Halo Reach level/firefighting problem

Hi my name is Time4Warp. The reason i made this post is because of Firefighting. About a week ago I bought the game and so far everyday i have been playing campain,firefighting,custom games,forge. I started alot higher than my freind which is a neigbor. When I started playing Firefighting with him the first time i got like 650 cR and now ever since i cant get any higher than 50 cR. When ever me and my friend plays he is second play im first i always get twice the amount of kills he does in Firefighting but can never get over 50 cR and he always get 650-1500 cR… I was wondering if there was some switch or button i could click to change that because it is bugging me a lot. Please,Please contact me if im just failing the round or there is something i need to do to make it so i get the most cR. PS: (Once he higher than me he started gaining the most cR…?)