if you're worried, order the ejection port cover:
http://www.airsoftparts.ca/store2/in...roducts_id=823
or you can order a new set since it's out of stock:
http://www.airsoftparts.ca/store2/in...oducts_id=1347
my dust cover always manages to find it's way open so having the port cover is a bonus. (it moves out of the way when you pull back the charging handle)