I couldn't afford a top end barrel - even an extra $50 would have been a stretch. So, I have a 1:8 twist Anderson Manufacturing phosphate coated barrel for my rifle. Came in at just under $100 which was all I had to spend for the barrel and it was the last part I needed. Granted, it may only last between 5,000 and 10,000 rounds. But, since I don't have a lot to spend in ammo either, at 500 rounds a year that's at least 10 years. Ideally, if you can afford a little extra, get a melonite or nitride barrel. You can find them for around $140 and a little less on sale. JSE Surplus often has them. Check CBC Industries also. If I were going to build another 5.56 I'd hold out for a nitride or melonite coated barrel. I'll likely do that with the 7.62 pistol I've started. If I don't find a 8" melonite/nitride barrel then I'll get a 7.5" one.