I`m not sure if this is the place for this, new to the board, and just need some direction. I received this JP Ent. AR10 in trade for a 556, and I`m baffled about what to do for optics. I would like to know what the best bang for the buck might be for this particular application. It has a 20" barrel (I believe). This is the model that can be shot as a single shot or semi-auto by adj. gas pressure on the side of the receiver. I would also like to know an approximate value for the rifle. It is built on an Armalite receiver. Any help will be greatly appreciated. Thanks, Chad.