On Halo 3, I have done 49 achievements (not the exact first ones), and have 1045

[The Meister]

gamerscore. Why don't I have? the katana or security helmet? THANKS

 

[will]

you need to have all the skulls to get all the armor, and i have heard about this, My brother has 1000 gamerscore (not first achievements) and didn't get it but my friend who also did random achievements but he got the katana, i just got 1000 gamerscore and i need to check whether or not i got the katana. I hoped i got it though, My friends said after i got 1000 gamerscore that i should get the katana. Hoped this helped.

 

[Lankey]

you need to earn the 49 achievements that the game shipped with in the first place. the extra ones do not count

 

[Martin]

Obviously if you have 1k gamerscore for Halo 3 you havent done the first Halo 3 achievements.. The Mythic Map achievements dont combine up to get the Katana or security.. Do the Original Halo 3 achievements..