my bushy 14" barrel has about 4-5000 rounds thru it.  most of it full auto.  i noticed yesterday that when shooting up close (15 yards) the bullet holes are elongated, indicating a fair amount of yaw.  going back to 25 yards, accuracy is right there, and the holes are perfectly centered as one would expect.  

question ~  is the close-in yaw due to excessive barrel wear and is that an early indication that the barrel might be getting worn and needing replacement?  it's off the scale when i checked it with a barrel erosion gage a while back, but was going to keep on shooting it until it just gives out.  

it's basically a "blaster" unit, that has seen its fair share of full auto and high heat that results from that type of shooting.  was considering getting a new LMT M4 upper in the near future, but was curious as to how long the current barrel might last.......

any experience based inputs appreciated....

Quoted: most of it full auto.

We talking burst to burst, or mag dump to mag dump??

Bottom line is you need a chrome lined barrel for full auto, and the longevity of the barrel just depends how hot you get it.  One point of throat erodsion is around 500 rounds if you don't over heat the barrel.  If you do, then figure around 150 rounds per point on the gauge.

If your barrel was chrome lined and is somehow "worn out" already it is almost surely do to excessive/impropper cleaning...  Do you clean it from the muzzle and/or without a bore guide?  Also, have you tried backing up to around 100yards to see if you get any key-holes?