Army of Two: The 40th Day

I need help getting the Barret M 107 50 Caliber Sniper Rifle unlocked, and suggestions would be awesome please. Until then i will keep looking for online for any advice. But i would prefer it comes from actual gamers who know how essential a good sniper rifle can be to a missions success. Thanks to you all for helping me out in this SNAFU, in advance.

where is wepon storage room in hospital to get the G18c

I don't knowhow to beat the big guy with the gatlin gun.

the chain gunner is really a pain, but breath and relax, you have to put your AI partner, or a friend, in a safe clear shot area of the Chain gunner, once your AI is in place you have to set him to aggro hold so he will be focused on your AI. Once the chain gunner has his focus on your AI quickly set up a shot behind the chain gunner, when in posistion you can then shoot the pack on the back of the heavy and take him out, use a sniper rifle or a machine gun with a scope and unload nearly a clip into it, once started done let up, he will turn towards you if you let off, finish him, get the cash and the ammo and move on, the same technique works also for the flame thrower heavy in later levles. Don't freak out or panic, that is the way you lose control of the situation. Hope this helps you out.

ok I just checked my 40th day there was an update and they seem to have fixed the glitch thanks