Halo 3 Security helmet

A while ago I unlocked the Security helmet in Halo 3 on the Xbox 360, and it was removed from my inventory within a few days. I checked the unlock requirements for the helmet on the Halo Wiki and it said that the helmet requires 1000 gamerscore in Halo 3 to unlock. I currently have 1125 and it’s still locked.
Am I doing something wrong? Do I need to do something else to unlock it?
Can someone from 343 or the community please help me with this?

That is weird do you have Katana? Because that also requires 1000g

> 2533275015111056;2:
> That is weird do you have Katana? Because that also requires 1000g

Katana requires 1000g and 49 achievements. I only have 44 right now, so I don’t have it. I really hope I get it once I hit 49, instead of being denied it like Security.

> 2533275015111056;2:
> That is weird do you have Katana? Because that also requires 1000g

1000g? jeeeezz…

me want helmet on reach!

I remember both, the security helmet and the Katana armor chest piece being a bit buggy if you unlocked them getting 1000 GS with the help of DLC achievements. They would unlock and lock again back in Halo 3’s glory days for all the people getting them through DLC achievements. No apparent fix was found nor it was patched, and the only way tho make it certain that they don’t disappear and re-appear randomly is getting the original 49 achievements the game launched with.