With any gun I have used while prone--if your try to aim while prone the gun will become disconneted from the reticle and point in a different direction.. I have found that when crouched and looking at the ground with the gun out it will mostly fix this issue but its not perfect.

1 Lay down prone
2 Aim gun around
3 Stand up and now try to aim your gun and see visibly that the gun is now not aimed at the reticle.
4 Try not to get mad when it costs you, your gear!

xbox version .63.148590