Originally posted by Molon on the AR15.com Forums:
A Tale of a 20” Colt A2 Barrel
This Colt 20” A2 barrel started its life on a factory-built Colt 6551. This was a pre-ban rifle, but this barrel did not have one of those evil, havoc-wreaking bayonet lugs; it’s otherwise essentially the same barrel found on the Colt M16A2 and M16A4 as well as “civilian” variants of those rifles. The barrel has a government profile, a chrome-lined NATO chamber and bore and a 1:7” twist.
I fired a couple hundred rounds through the barrel while zeroing, chronographing various loads and doing some informal shooting. I did not conduct a formal accuracy evaluation of the barrel at that point in time. After that, I replaced this barrel with a Colt M16A2 barrel with the attending evil bayonet lug to create my M16A2 clone.
This barrel sat on my parts shelf collecting dust for a while, until I decided to sell it. I ended up selling it over the Internet. Three months after the buyer received this barrel, he sent me a message demanding a full refund for the barrel claiming that the barrel was junk and that it was never going to shoot accurately. While I was under no obligation whatsoever to give the buyer a refund after having it in his possession for three months, I did so anyway, minus a “restocking fee.”
After the barrel was returned to me I decided to conduct a formal accuracy evaluation of the barrel. I installed the barrel on a Colt flat-top upper receiver and free-floated the barrel with a 12” KAC free-float hand-guard. I conducted the accuracy evaluation from a distance of 100 yards from my bench-rest set-up using my hand-loads topped with 55 grain Sierra BlitzKings.
This barrel turned in a 3-shot group at 100 yards with an extreme spread of 0.180”.
This barrel produced a 5-shot group at 100 yards with an extreme spread of 0.516”.
A 10-shot group fired from this barrel at a distance of 100 yards had an extreme spread of 1.085”.
Six 10-shot groups fired in a row from this barrel at a distance of 100 yards had an average 10-shot group extreme spread of 1.35”.
Not too shabby for a “junk” barrel and actually, as good as anyone could expect from a chrome-lined, NATO chambered government profile barrel. In fact, this was one of the most accurate 20” government profile barrels that I’ve ever tested.