Complete the following achievements to unlock Xbox Live Gamerscore points.

Achievement	How to unlock
2 guys, 1 Coop ( 10 points )	Complete a Co-Op mission with just 2 people.
Bulletproof ( 5 points )	Complete a Co-Op mission without dying.
Dodge this ( 10 points )	Achieve a kill chain of 10 or more in any Advanced Co-Op mission.
Friends indeed ( 5 points )	Complete a Co-Op mission without anyone dying.
Have posse, will travel ( 15 points )	Complete all Co-Op missions.
Stake a claim ( 5 points )	Gold medal any Co-Op mission.
Struck gold ( 10 points )	Gold medal all Co-Ops missions.
The mother lode ( 20 points )	Gold medal all Advanced Co-Op missions.
Well done ( 5 points )	Complete a Co-Op mission.
You rule! ( 15 points )	Complete all Advanced Co-Op missions.