I thought hard about Stoner on my last build, but I couldn't get past no knowing exactly who makes it. I hear it is shaw, but you never know when Midway will use a different manufacturer.
I went with Rainier Arms 16", 5R polygonal, mid length gas, 1:8, NATO, medium contour barrel. I couldn't be happier. Accurate and light.
223 wylde is good to go. It can shoot both 5.56 and 223.
For that type of competition, I would get a 16" or 18", 1:8, NATO or wylde, medium or gov profile, mid length gas.
Don't go to heavy on the buffer. Faster follow up shots are better in practical rifle or 3 gun matches. A good set up like at low mass carrier, low mass buffer and good spring will make double taps quicker. You can lighten a buffer by switching out internal weights with aluminum bar or tube. Don't skimp with homemade or cheap carriers. If you get a low mass carrier get JP. The cheaper low mass carriers can wear out your receiver. Any reduction in weight in the carrier is good. Using a semi auto vs full auto carrier will help. The lighter carrier will help reduce lock up time. A good spring is important to prevent bolt bounce. If you go real light with the carrier and buffer, you will need an adjustable gas block. So I would suggest to start with a good buffer spring, semi auto carrier and lightened buffer. Worry about a low mass carrier later. For buffer springs either Tubbs or JP.
Other important comp parts are trigger and a brake. A good 3-4lb trigger; timney or Geissele. A brake is very important to help control the muzzle during those fast double taps; rolling thunder or STC Titan. I have the Titan. I think it is the best I've shot. It is big and LOUD, but it works.
a quality name free float tube is all you need for a forend: Midwest Industries, AP customs, etc. As long as you can fit with your barrel. 12" or 15". I prefer 12" AP custom.
My build is 7lbs with scope.
