I shot in my first National Match competition last month and it was a blast! I used an H&R M-1 (as issued)that I have and I didn't do to bad for a rookie. Everyone else had AR-15's that were built for competition. I have an AR-15/A1 with the old style sights. Would it only require me to change the upper by purchasing a new Nat Match type upper to combine with my lower to get me started?