The achievement "Scrooge" is unlocked by saving 1000 military grade rounds but how to reach 1000 over the course of your 10 hour journey in the metro and the now apocalyptic Moscow?
Well there are a few ways you can earn these rounds quick and easy!
1) Ammo traders. You will generally find these guys around civilian populated areas and will be buying and selling ammo to you. If you aren't going for the achievement for getting a kill with every gun then sell all the ammo you get for the guns you aren't using at the time.
2) search every box, locker, dead person you find throughout your journey as they may very well have the military ammo on them.
3) safes! Now safes are where you can literally strike gold for this achievement as sometimes they may hold ALOT of this type of ammo, I personally found 150 in a safe on the level "FRONTLINE". To open a safe you must search for a key which can be found either somewhere earlier in the level but most of the time will be found close to the safes area and is noticable by the red tag the key has on it.
Warning: DONT spend to much ammo as I got to the second last level and barley found enough to get me to 1000. Also If you're using an assult rifle/sub machine gun class be carefull NOT to use this ammo as it is usable and if you must use it try limit how much you use as it shouldn't take more then a few bullets to kill an enemy.
If anything needs to be changed please let me know!
Note: I am currently working on a guide for the safe keys and will post ASAP! :)