Always, ALWAYS, check the exp date on the batteries no matter where you buy them from or what brand they are. Just because you buy it new in package doesn't mean it is still a new battery. I recently went to buy batteries at wal-mart because it was closest and managed to find a pack that expire in 2010 and yet was still up for sale. Make sure you buy fresh, brand new ones.
As for the trigger screw, I never had that issue, but I will agree that a simple da of blue loctite will take care of that in a jiffy.
Laeti vescimur nos subacturis
Dangerous Power - Virtue - Exalt