I'm considering the following options for a build and looking for opinions. Start with a Bushy lower with tele stock. Then the upper will be an A2 with either the 11.5 barrel and pinned XM 177 FS. Or the 14.5 barrel with FS. I also want to put a Bushy rail on the top of the handguard and mount a Leatherwood 1x50 Red Dot. Opinions on the barrel lengths and the mounting of the red dot are welcomed. I want the dot to cowitness with the sights. The sight would be mounted just in front of where the front of the carry handle meets the top of the receiver.  Anyone tried this set up? Pros and Cons. I know there will be a slight velocity drop with the 11.5 barrel. Let  me know what you think.