Errrr misconceptions kill me. I'd respond earlier but I'm lazy. Still, now that there are multiple problems I feel motivated.
:P
Back when Halo 3 was released, to get the Katana and Security helmet you needed to get all the achievements. There were 49 of them for a total of 1000 GamerScore (GS). In Spring of 2008 the Legendary Mappack was released. With it were new achievements for the mappack.
These achievements, however, caused issues. It glitched the armor permutations. Suddenly people were getting them at 320GS, others didn't get it at 1200GS. Achievements have been added multiple times since then. Nothing helped the issue.
In short? I've seen people have it with 350 GS, and other haven't had it but they've had 1700 GS. It's more or less random this day.
However, with this, another glitch emerged. People were unlocking it, but sometimes ti would randomly lock itself back up again. There is no 'solution' to this problem. You can only prevent it. The way to prevent it is by obtaining all 49 original Achievements. That means earn every single achievements that doesn't require a DLC Map or is a Vidmaster.
So there's the complete explanation folks.
Posted by: Bewegungskopf
I may need 300 EXP to get the Officer Achvmnt? /
Or, if I get to 20 skill level? Like that's ever gonna happen.50 experience in an individual playlist gives you the officer rating. Looking at your service record... you have 24 experience in Social Slayer and 24 in Team Slayer. So if you win 26 games in either playlist (without quitting or lagging out of any) you'll have the achievement.