Ok, maybe I am being too anal retentive about this - you tell me. I own 3 AR's with bare muzzles. All were purchased new and all are from the same manf (one of the top four companies - A,B,C,RR). I am purposefully trying to Not say what company because I do not want to blame them for something that is my fault (being too damn anal).
Of these 3 AR's, I see defects in the chrome lining in 2 of them. If I shine light down the muzzle, and examine the barrel with a magnifying glass - here is what I see.
The first barrel's blemish is easy to see in the photo. The blemish is very shallow and can Not be felt with a straightened paper-clip.
Below is the shallow dimple blemish
Below is the second barrel with pits
The second blemish is more difficult to see from a photo. I have examine it with a loupe. At first glance, it appears to be pitting - extremely small diameter pits but intense in the number of individual pits. But upon closer examination, it appears that the chrome-lining failed to get complete coverage of the plain steel surface underneath. The picture above is somewhat misleading. In the pic, it appears that the bottom of the pits is bright chrome color. But, actually, the surface is chrome with the pit bottoms being black (as in plain steel color). It is as if the chrome lining process "ran dry" toward the end of the barrel. Kinda like painting with a paint brush and your brush begins to "run dry" at the end of the stroke. Or, kinda like spray-painting and the spray can "runs empty" and can not produce full coverage. To further support this theory is the fact that I see no chrome lining at the crown. With my other 2 AR's with bare muzzles, I can see the chrome lining terminate along the crown - the lining actually covers the crown and then stops.
This blemish does cause inconvenience. I have heavy copper fouling, within 50 rounds, caused by the blemish. I suppose the copper is scraped off along the "pits". I was hoping the pits would smooth out and the copper fouling would stop as the barrel broke-in. After 300 rounds, it still gets heavy cooper fouling along this blemish area. Because of this blemish, I use Sweet's on this barrel after each range trip (about 6 range sessions with 50 rounds each). I did not leave the Sweet in beyond 15 minutes (remember that I am anal). I also rinse out the Sweet extremely well. PLUS, I do remember seeing this blemish when the gun was new. At that time (when the gun was new), I was just thinking it would go away after a few rounds.
These two blemished barrels cause me to wonder if non-chrome, or stainless steel, barrels would be a wiser decision for my future purchases. This also causes me to wonder what my M4 barrel looks like - which I cannot examine because of the postban brake. Also makes me paranoid what does chrome line barrels look like along the full length where I am unable to examine it (I am not rich enough to afford a bore scope $$$).
On the positive side, these two "blemished" barrels do shoot 1 m.o.a. groups. I have verified the grouping from the benchrest, 100 yds, handloaded Nosler Ballistic Tip 55 gr, Leupold III 20x.
Have you ever really examined your chrome lining up close (bright light and magnifying glass) ?