Im am trying to decide between a Ops Inc 12th model or a AAC M4-2000. It will be on my ar15 with a 16" barrel for now. I would like to have one with a long enought flash suppressor or com. to make a 14.5" midlength barrel 16" when permanitly attached. The Ops is kinda looking good for a future SPR build. Any help would be great.