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A Tale of a 20” Colt A2 Barrel

Originally posted by Molon on the AR15.com Forums:

Link to forum post.

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.

…..

The downside to the AR15 ambi-safety.

 

One of the overlooked but great advantages of the AR15 is its easy to actuate safety/selector switch.  Some other guns, actually most other guns have perfectly serviceable safeties but not ones that can so easily be used.  Because of this many teach to place the AR15 on safe often, even when reloading.  Now to debate the merit of that isn’t the point of this article.

Now when manipulating the rifle left handed or left handed only, I would use the thumb of the left hand to flip the safety off and I would leave it off until such time that I knew I was not going to need to immediately shoot.

It is not that awkward for me to flip the left side safety with the thumb of my left hand, but that is a brief moment when you don’t have a good grip on the gun.

So on many of my rifles I run ambi-safeties.  I’m rather fond of the KAC models with scalloped right sides.  I’ve also use or owned Colt, LMT, and DSA ambi safeties.

You would think that an ambi-safety would be a pure upgrade with no downside.  Unfortunate not.  The easy to reach AR15 safety/selector has the downside of moving through the same space that the trigger finger would occupy.

So regardless of if your trigger finger is on the trigger, or off the trigger pointed forward along side the lower, that safety lever can and most likely will hit your finger.

This is the reason why KAC offers a scalloped right side trigger and Colt’s ambi-safety is shorted on the right side, etc.  This helps a the safety clear the trigger finger of the right handed shooter.

So what if your left handed?  Sucks to be you.  Or you could buy one of those rather expensive completely customizable safeties.

Ultimately this is a training issue.  Regardless of the type of safety you run, you need to be able to actuate it one handed with either hand.  I found that it was rather different working the safety if your holding the rifle with both hands, vs working with the right single-handedly.  When your support hand is holding the bulk of the weapons weight, it is no problem to shift your firing hand as you work the safety.  However if your holding up your rifle with just the one hand, trying to move your grip as you toggle as safety is just plain awkward.

Upcoming

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A little teaser for a couple of things to come over the next week or so.  Things got a little busy for everyone, then the weather hampered outside range testing.

Pictured for upcoming testing is the KRISS Vector and the excellent HighCom Security  active shooters kit plate carrier and two level 4 stand alone plates inside.

Accuracy testing for the Vector will hopefully be done this weekend for a review to be posted early next week.

 

Our Favorite Gun Blogs PT 1

We don’t  often speak about other blogs  here.  One reason for that is that more than a few of the bigger names have stolen some of our posts and re-posted word for word our content.  But there are a few that are outstanding in my opinion, and one in particular that is so good that is is the one website I spend almost as much time at as I do our own website here.

Weaponsman.com

To use the owners words to help set the tone for the website.

“WeaponsMan is a blog about weapons. Primarily ground combat weapons, primarily small arms and man-portable crew-served weapons. The site owner is a former Special Forces weapons man (MOS 18B, before the 18 series, 11B with Skill Qualification Indicator of S), and you can expect any guest columnists to be similarly qualified.

Our focus is on weapons: their history, effects and employment. This is not your go-to place for gun laws or gun politics; other people have that covered.”

As you can read from the “about” blurb from the wesbsite, the eponymous weapons man is indeed more than qualified to talk about small arms.   Though it is a very rare day indeed when he is only talking about small arms, or larger weapons of all types  from those used in the heavens to below sea level and in between.   That is one of the many reasons I love the website.  He touches on a variety of topics, none of them ever boring.  A personal favorite being the “when guns are outlawed then only outlaws will have ….  toilets, chainsaw, defenestration etc etc , whatever was the cause of death in the news report being spotlighted. Point being to  give none stop evidence  of what we  already know.  Banning guns will not stop murder or  accidental death.
Weaponsman  AKA Hognose, of course has multiple  technical and historical posts  on a variety of weapons,  some rare and some well known  to the gun world.
Being constantly in the thick of tech gun info myself,  some of the other posts I enjoy the most are the ones where he talks about the Special Forces world and gives  tidbits from that world only a few will ever experience.  The USSF posts often range the full history of the Green Berets, often from Vietnam to more recent times.  best of all. there is no snobbery there. No elitism. No “stay in your lane” if you want to ask a question or make a comment ( as long as it is not idiocy of one variety or another of the many varieties) in the comment section.   The comment section itself full of wonderful knowledge and experience  from the regulars.  Some of those regulars being people you may and should already know like the irreplaceable Daniel Watters from the 5.56 timeline and fellows like Ian  from Inrange TV / Forgotten weapons not to mention any amount of SF people old and new.  And of course myself.
You may even run across articles and posts speaking about our work here ,as he reads looserounds which is very flattering.
If you only want the tech stuff there is plenty of that. All posts come with multiple sources and usually links to where to buy the books or free PDFs , and other means.   A sample from the Best of Weaponsman gun tech section below  copied from the website.
  • The SAWs that never WAS: Intro, and XM106. This introduces the series, and the ugly duckling of the competition, a bizarre M16A1 variant with quick-change barrel, but still magazine-fed. Published 28 Oct 13.
  • The SAWs that never WAS: Part 2, the XM-248′s forerunner, XM235. The Rodman Labs XM235 was a radical reconception of the light machine gun which was designed to increase accuracy and reduce unintended dispersion on target. We mention in passing its abandoned XM233 and 234 competitors, all chambered for a 6.0 x 45mm cartridge. Published 31 Oct 13.
  • The SAWs that never WAS: Part 3, XM248. Rodman couldn’t go to production, so the commercial makers of the XM233 and XM234, Philco and Maremont, competed for the contract. Philco (later Ford Aerospace) won, and began to make changes to the XM235, as requested by the Army, producing the XM248. Published 2 Nov 13.
  • The SAWS that Never WAS, part 3b: the feed of the XM248. The ratchet-driven sprocket belt feed of the XM235/248 is examined using the patent documents as a basis. Published 4 Nov 13.
  • The SAWs that never WAS: Part 4, H&K XM262. Heckler & Koch’s entry was initially just a baseline for comparison of the Army’s own designs, but it performed well enough to make it into the final four (with the 106, 248, and 249). Published 9 Nov 13.
  • The SAWs that never WAS, Part 5, XM249. Like the H&K XM262, the XM249 was initially just entered to compare the FN light machine gun to the Army entries, but it ultimately beat them all. Published 23 Nov 13.

If you like our page, I strongly recommend WeaponsMan, it is highly addictive and always entertaining with a high does of humor mixed with technical discussion.

This is the first website to be mentioned in this series because it stands above all others that will come.  It has my highest recommendation and I hope you go check it out and enjoy it as much as I do.