In most states I believe it is fine to purchase type III armor. The issue in some states is you must not have any previous convictions. In the UK its completely legal.
a 50 cal sniper Standard body armor without any extra insert plates is generally rated as Type IIIA or less. This type of armor cannot withstand any real rifle bullet. At best, it can stop submachineguns and high-powered pistol round. Type III and IV armors usually have some sort of ballistic ceramic plate inserts. These inserts can stop a single (under ideal conditions 2-3) bullets per plate of up to 7.62mm Armor Piercing.
Three (3) days.
Complete all aspects of the game required to unlock each type of armor. You can google a list of these actions. Recon is now an un-lockable armor as well, complete all "vidmaster" achievements.
http://hubpages.com/hub/Halo-3-Armor
No, there is no armor in Halo 3 that has a knife in the shoulder.
Mark IV is a type of armor in the game: Halo 3. This is a evolvement from the Mark V armor in the previous Halo games; Halo:Combat Evolved and Halo 2. The armor is also called the Mark 6. In the game it is an armor that is worn by the main charecter: Master Chief. In the multiplayer game it is an armor that you automaticaly wear in the matches.(there are other armors to wear during matches)
you can get some in campigan like hayabusa,eva,and eod to unlock them you have to hayabusa=find all the 13 hiden skulls eva=beat campigan on normal eod=beat the campigan on LEGENDARY
No there isn't, the ODST is just a Helmet there is no body or shoulder to the armor. To get the helmet just play online until you get to the rank of private which can take as little as 4 games.
recon armor
There is no Brute armor in Halo 3, only Elite and Spartan models.
mop level 3
go to http://hubpages.com/hub/Halo-3-Armor