Well, i have been contemplating and now, after watching the guys shoot CMP today, i have decided i want to shoot that. I have no rifles that fit the criteria so i need to buy/build another. If i understand the rules correctly. I need a 20" basic A2 or A4 type rifle. A quad rail is acceptable and a trigger up to 4.5lbs is also ok. I want a 5.56 with 1/8 or 1/7 twist. Now, searching the web i realize not many complete 20s are available and uppers seem to be hard to find. Gunbroker has a few but they are 1/9 twist. What are some makes and models i can buy off the shelf? on the web they are out of stock or don't offer what i want. With a model, i can call a few local dealers and see if they can get it. Also, do any of you guys shoot CMP with the AR? Do you have any tips or tricks?