So I found a barrel in the back of my closet that I bought back in 01’ right after the ban ended and I figured I would use it for a build and never did. I’m in the middle of a build that Im using another barrel on so I figured I would use it for the next build. It’s a DPMS 16" heavy barrel with a 1 and 9 twist. Has anyone had any problems with there barrels like they have had with the rest of there parts or am I go to go with the barrel?
Many times they have .223 chambers which can make the rifle blow primers when shooting 5.56mm NATO pressure ammo. This can be remedied with the use of a Ned Christiansen 5.56mm neck and throat reamer if you encounter the problem.
I had a DPMS 1/9 11.5" that I made into an SBR on a form 1, it was marked 5.56 however. It was a chromemoly heavy profile, but caused me no problems whatsoever after about 1000+ of M193 and 55gr WWB, and about 200 rounds of Radway Green. My chief complaint was it was too heavy. I just removed it and sold it this week, and rebarreled with a lightweight profile barrel which is much more to my liking for my usage.
If dire need arose, I would still grab my 6920, but despite all the bad press, I had been quite satisfied with this DPMS barrel and the upper it was previously attached to. I do maintain my weapons meticulously. I believe the DPMS barrels are all 4140, but if it’s not rollmarked 5.56mm, as stated above, you might want to make sure what chamber it actually has.
I have the Colt 6721 16" 1-9 Heavy Barrel, I doubt I’ll ever have to mount a 203 on somthing. What have you heard about Colts and have you heard anything about the ?6721
The 6721 is a Great rifle. A lot of people prefer lighter profiles though. Shouldering the carbine one handed is hard work unless you have Popeye forearms! 
I have an LE6721 that I got during the ban. It’s my current Home D gun. I prefer the 1/9 twist since I never shoot anything longer than a 62 grain bullet.
Colt QA and materials are top notch and you can’t go wrong from a quality standpoint. They tend to hold value a bit better as well.
My two cents on DPMS barrels, Myself and several other co-workers bought DPMS M-4 rifles before the ban expired our local dealer was really humping them as the best AR15 on the market. As I began to further educate myself about the rifles I read about numerous incidents of DPMS rifles blowing primers while using surplus 5.56 ammo.
I contacted DPMS via phone and e-mail inquiring if I in fact had received a .223 saami chamber or did I receive an actual 5.56 chamber on a rifle marketed for an LE aplication, On a side note I completed all the paperwork for a LE purchase for this rifle. The response of DPMS was less then stellar telling me "It is what it is " I go the impression that they had no clue what chamber was or is being used.
Needless to say it was replaced, I can’t say that it was not accurate but I now own a Colt and a Stag that I built myself after attending the Colt armorers course. Both of my guns have chrome lined chamber/bore and 5.56 chambers.