I am currently working on an AR-15 build and in my search for low cost high quality parts I stumbled across MAS Defense. My experiences with them have been very good, their parts are affordable and their sale page is updated regularly. So far I have ordered a 16" .300 AAC Blackout barrel and muzzle brake from their site and have been very satisfied with my purchases. MAS ships 2 day delivery with insurance for a very reasonable price (the barrel was $12 I think?) and offers insurance on their shipped items. I have not had been able to test the accuracy of the barrel yet, but my dealings with MAS will have me going back to them for my next batch of parts.