A drop forward is a peace of metal that drops ur asa (the part that ur tank screws in to). The purpose of it is to drop ur tank placement to a lower position to make it more comfortable for u. I have one on my pilot but not on my dm4 its really all about ur personal preference. Go to ur local field and ask to hold someones gun that has a drop forward on it. Get a feel for it fire a few shots and see how u like it. Good luck and welcome to the forums.