@ BAC......
Yea, it's the Gov. barrel, my I (and my smiths) refer to ANY AR that has the smaller barrel as a thin barrel, simply because it has the same diam. in the cut down portions as the lightweight barrel (see SGBs AR? The barrel is smaller than the flash suppressor. A Lightweight barrel.) This makes the barrel only as strong as it's thinnest part. Now in my experience in the military, and outside as well, this is a weak spot for the AR platform. Yea the lightweight barrels are lighter, but they overheat faster. Same as a "govt" barrel w/ the 203 notches. It's where the barrel will fail first. This is why I always recommend the heavy or (my fav) the bull barrel. There is absolutely nothing wrong with shooting a lightweight barrel, it's just not what I want, nor recommend to a serious shooter.
This IS of course….. MHO as always! :yup: