halo 3 security armor help ????????

[Phil]

i have a 910 gamerscore and i still cant get security shoulders and ive been working so hard for them and i have 39 achievements like it says i need need help!!!!!!!!!!!!!!!!!!!!!
dont ask what achievements i have im not going to answer, you can tell me what i need, dont ask, please...
yes its all the original achievements no new ones so special stuff just wat i said

 

[Kaiser TheGreat]

Did you unlock the "Marathon Man" achievement?

 

[Matthew L]

i think you have to unlock all achievements

 

[Brandon]

go to the home page of halo. u will find ur answer there

 

[iDontCare]

All the achievements need to be from the first 49, not any of the new achievements...