Nothing but the best that the lowest bid can offer! The 3 MOA is the extreme, an indicator for replacement, the NATO ammunition is also factored into this. NATO's requirements are not very demanding of the manufacturer. Most A2's will hold much better but with iron sights few notice as long as the rounds strike center mass on a human torso sized target the misson is accomplished. I guess my point is that if you start with a quality barrel holding .5 MOA, many thousands of rounds later the performance may slowly degrade to 1 MOA, depending on the purpose of the weapon that is not horrible. Until you are capiable of shooting better groups then your rifle/barrel can hold there is no sense in replacing the barrel.

The official testes on the A2 with the latest barrel twist (1:9 vs the A2's origional 1:7) shows over 6,000 rounds fired before any detectable spread in group size and over 10,000 rounds fired before a "noticable" differance was recorded. Quality ammo was used (produced by Winchester USA) NATO SS109 (U.S. M855) Ball, 62 gr flying at about 3,200 FPS at the muzzle (20" test barrel). They did have varying results using this round in the older slower twist barrels (1:12 had accuracy problems, bullet lacked flight stability) and with the faster 55 gr. in the 1:7 twist barrels (barrel errosion occurred sooner than with the 62 gr / 1:9 setup). Still noticable group spread did not occur until after 6,000 rounds.

All that said and making a statement based on these test results; an average shooter should get at least 6,000 rounds from a quality barrel with close to new accuracy. Some slightly less, some more depending on the rate of twist, bullet weight, and speed.