This is a list of parts that can be swapped from AR-15 to AR-10 and vise versa. It is a word document download that is short and to the point. These questions come up often so I (Curtis Obst) figured it would be a useful thing for our customers and followers. Enjoy! The webstore will not allow me to make this item free for some reason. Feel free to print this up or even share it. If its worth the dollar to you we thank you.