Say Hello to my Little Friends Achievement
Say Hello to my Little Friends45
Purchase the MP7, M134, DAO-X Protecta, MGL MK-X, and the M107 Light Fifty.
After completing the game on any difficulty, all primary weapons are unlocked so you can save money on 3 of the 5 guns (M134, DAO-X and MGL MK-X). Just purchase the remaining two guns (MP7 under 'Secondary Weapons' and M107 Light Fifty under 'Special Weapons') to get the achievement.
Complete the game on Professional (see "Elite PMC") to unlock every weapon and the achievement.