Archive for the 'AR-15s' Category

Shooting Illustrated.

In addition to recording a series of internal and external measurements, I visually inspect every barrel that comes into my hands from end to end, inside and out. Special attention is paid to the crown, feedramps, gas port, muzzle and bore. The crown is checked under high magnification for burrs, gouges or other imperfections that can cause projectiles to leave the barrel inconsistently, diminishing potential accuracy in the process. A magnifying glass or jeweler’s loupe and a good light will go far to help you see how this critical transition from bore to muzzle face has been cut. Most barrels have some form of recessed crown that are cut at varying angles, depending on the maker and barrel type. My experience is that the degree of crown is far less important than how cleanly cut and uniform it is.

Damage to a new barrel’s crown can be caused at any point along the way between production and installation and this is certainly not unique to the AR. Crown damage on any rifled barrel should be carefully evaluated to ensure it is not going to cause problems during firing. If the barrel arrived with an already-damaged crown, I would contact its source in hopes that they will exchange it for a new one before troubling yourself to fix it.

Flawed or damaged crowns can be cleaned up through the use of either hand crowning tools or a machine lathe. If you are only dealing with a single barrel, the most cost-effective route to repair is through a gunsmith. However, if you lack a lathe but are regularly dealing with banged up crowns, investing in a good hand crowning tool will pay for itself in the long run.

After checking the crown and if the muzzle is threaded, I always “chase” the threads with a properly-sized die to ensure they are fully cut and cleaned up. Just behind those threads, the shoulder is the next area that I check. If you plan to use a sound suppressor, this shoulder should be square with the bore and threads to ensure proper suppressor alignment.

This is true for both direct-thread suppressors and those that use QD mount-style muzzle brakes and flash hiders. If your muzzle device seats on the face of the muzzle instead of the shoulder, the muzzle face will need to be checked instead. I seldom see damage in these areas, but occasionally a barrel comes from the factory with a flaw that would prevent a muzzle device from seating squarely. I use a lathe to slowly spin barrels while I check runout [with gauges] on shoulders or muzzle faces, then remedy any flaws at that time. Again, a gunsmith or machinist can perform this check in just a few minutes and even if it needs to be re-faced, it is a simple operation.

Whether or not you have this check performed, I strongly recommend that at a minimum, you use an alignment rod to verify that your suppressor and bore line up correctly before live firing the system.

Sliding back along the barrel a few inches, we should find a gas port that is drilled at top-dead-center of the barrel when mounted in a receiver. Most manufacturers drill their ports once the barrel extension has been installed so that the index pin, which nests in the upper receiver’s index notch, actually performs its namesake function. Nonetheless, once in every hundred or so barrels, I find one that has the gas port and index pin out of alignment. If the misalignment is more than a couple degrees, there is a pretty fair chance that a properly timed gas block will result in reduced/restricted gas flow, impeding operation and increasing wear of the gas block itself. Unfortunately, there aren’t any great options to repair this problem. If you lack the correct tooling to install and remove a barrel extension, this manufacturing error is best left to a gunsmith or (preferably) the manufacturer to remedy.

A simpler and far more common problem is having an undersized gas port. A decade or so ago, barrel makers tended to oversize gas ports, especially on service-grade barrels. The prevailing wisdom being that it was better to have too much gas and keep the gun running rough and dirty than too little gas preventing it from running at all. It was left up to gas block makers and gun builders to figure out how to modulate the excess gas, especially when using a sound suppressor.

The situation is nearly the opposite today, as both match and rack-grade barrels are frequently sold with ports that are either undersized or only marginally functional as-is. Therefore, gun builders oftentimes must open ports according to the configuration of the gun and its intended use. Opening a barrel’s gas port is not difficult, but knowing how far to open it is a critical part of the process. I measure every gas port that comes across my bench and cross-reference it with a database of the 1000+ barrels I have previously measured to ensure that the size is appropriate for the length, caliber, gas system, gas block type, planned suppressor use and bolt carrier/buffer system weights.

Well, he’s a better mechanic that I am, he has a world of experience, and he has tools that I don’t.

Other than that …

The advice is to get both.  But I found this bit interesting.

Armalite continued to develop and improve upon the AR-10 concept. Under the direction of Stoner, replacing the composite aluminum and steel barrel that may have ultimately been responsible for the military’s decision to go with a different weapon. Stoner had never liked this barrel. It proved a spectacular failure during torture tests demanded by the customer. The composite barrel had been suggested by Sullivan. This marked the moment when major Armalite design decisions started moving in Stoner’s direction.

That’s information I didn’t know.  It seems like there’s something I learn about the Sullivan/Stoner relationship every time I read an educated piece on this part of history.

Recoil.

This is a very well written and informative article.  For those who are wondering, the M18 is the M-4/AR-15 variant with a typically shorter barrel, usually sporting a quad rail.

I see the need for this sort of weapon, given the focus on CQB in recent years combined with the fact that suppressors are now ubiquitous in the U.S. military, so a 10.5″ barrel isn’t really 10.5″.

But it does cause problems, including lug breakage, high pressures, etc.  This article discusses some of the ways to mitigate those issues, including coated BCGs, adjustable gas blocks, and so on.

But just be sure to remember that when you go altering the design the engineer gave it, you introduce all sorts of unintended consequences.  The machine will usually perform its best when unaltered from the original design, assuming the engineer is good.

And Eugene Stoner was good.

In this video West Virginia attorney John Bryan details the decision of the Fourth Circuit concerning his client.  It’s a long video, but if you want to read the decision it can be found here.

This case should have been easy and quick.  In U.S. Versus Black, the Fourth Circuit had this to say.

Being a felon in possession of a firearm is not the default status. More importantly, where a state permits individuals to openly carry firearms, the exercise of this right, without more, cannot justify an investigatory detention. Permitting such a justification would eviscerate Fourth Amendment protections for lawfully armed individuals in those states. United States v. King, 990 F.2d 1552, 1559 (10th Cir. 1993).

In this West Virginia case, Walker wasn’t a felon, and West Virginia permits open carry of firearms.  But you see, Black was carrying a handgun, and Walker was carrying one of those evil ARs, so the Fourth Circuit had to do something.

Contrary to Walker’s interpretation, the Black decision does not dictate that, in a state like West Virginia where it is legal to openly carry a firearm, the act of openly carrying a firearm can never engender reasonable suspicion.

Keep your eye on the card – now you see it, now you don’t.  Because we say so.

They go on to differentiate between handguns carried in a hip holster and the awful, wicked AR-15, which is certainly the weapon of choice by mass shooters – so says the media.  That eighty people per weekend get shot in Chicago with handguns isn’t really germane.

Nor is it germane that gangs result from the evisceration of the inner city due to fatherless families and financial encouragement to have children out of wedlock, or that Coyote hunting in West Virginia and elsewhere is commonplace and a man walking in the middle of nowhere preparing to hunt Coyotes should be fairly routine stuff to the tyrants in the police force of Putnam County.

[Note: One reason guys hunt Coyotes is because they sit in wait for deer to deliver fawns, and then eat the young, disturbing the deer herd size.  Coyotes are predators.  In groups they will also threaten people.]

What matters is that the Fourth Circuit is out of Richmond and probably reads every major rag published daily by the legacy media.  Having said all of that, the real root of the problem lies somewhere else.

It lies with the folks in Putnam County, and especially with Sheriff Bobby Eggleton.  A group of people will always take on the personality of its leader.  The offending officer in this case was vulgar, obscene, rude and tyrannical, and couldn’t go three words without cursing at Mr. Walker.  I suspect that’s what the Sheriff is like too.

So the Sheriff is to blame, but probably also the County Commissioners, who should be run out of town on a rail for allowing this sort of thing to happen.

Sheriff Bobby Eggleton: beggleton@putnamwv.org

County Commissioner Brian Ellis: bellis@putnamwv.org

County Commissioner Ron Foster: rfoster@putnamwv.org

County Commissioner Andy Skidmore: askidmore@putnamwv.org

Prosecuting Attorney Mark Sorsaia: prosecutingattorney@putnamwv.org

Matt Bracken writing at American Partisan citing a 1969 American Rifleman article.

I was told by the so-called experts that the M16 rifle is not accurate beyond 350 meters.  But with my rifle fitted with bipod mount and scope sight and firing tracer ammunition, I can reach out and drop a walking enemy soldier at better than 700 meters range …

Our 5.56mm bullet will severely batter a man wherever it hits him.  I would rather stop a half dozen bullets from an AK-47 than one from an M16.

It’s America’s rifle.  If it was a “good” rifle then, I’d say it’s variants are great rifles today.

Another case shot through the gun.

Fox News.

The 9th Circuit Court of Appeals temporarily blocked a federal district court ruling that would have repealed California’s assault weapons ban.

In a Monday panel decision in Miller v. Bonta, the appellate court put the June 4 order from District Court Judge Roger Benitez old hold as the court awaits the outcome of another case. Benitez had ruled that the ban violated the Second Amendment.

“The district court’s June 4, 2021 order and judgment are stayed pending resolution of Rupp v. Bonta,” the court said. “The stay shall remain in effect until further order of this court.”

The Rupp case, which also deals with the assault weapons ban and has already been briefed before the Ninth Circuit, had also been put on hold as the court handles other Second Amendment cases that could effect it.

You knew that would happen, right?  And you know how the Rupp case will end, right?

The Ninth Circus strikes again.

I say more in the post title because there’s already been a lot of that testing.  Watch Andrew’s testing and listen to his points all the way to the end, and then I have some remarks.

We’ve discussed this many times before, and linked various articles on this: Small Caliber Lethality: 5.56mm Performance in Close Quarters Battle (note that links to this paper in previous posts are broken but this one works), 5.56X45mm Versus 7.62X39mm, AR-15 Ammunition and Barrel Twist Rate, and a CFD analysis entitled Prediction of Projectile Performance, Stability, and Free-Flight Motion Using Computational Fluid Dynamics.

I had never even once believed that the reason for a change of barrel twist had to do with yaw inside tissue.  The real reason is found elsewhere.

Accuracy cannot be assessed without addressing the rifle barrels’ twist-rates. In the early 1980s the M855’s 62-grain bullet was developed for the M249 Squad Automatic Weapon (SAW). For purposes of interoperability, the same load was adopted as the M16A2 rifle’s standard ball as well. A February 1986 U.S. Army study noted that the M855’s bullet required a “1:9 twist [which] would be more appropriate for the M16A2 rifle, improving accuracy and reliability.” Multiple studies confirmed the 1:9-inch twist requirement.

But then a problem arose. The U.S. military’s standard M856 5.56 mm tracer round was longer, heavier (63.7 grains) and slower than the M855 ball, and simply would not stabilize with a 1:9-inch twist barrel. Thus, despite it doubling M855 group sizes, the M16A2 (and later, the M4) specified a 1:7-inch rate-of-twist barrel to stabilize the tracer round. It remains so to this day. Therefore, M855A1 was test-fired with both 1:7- and 1:9-inch twist barrels, and it was verified that this new cartridge is consistently more accurate in the latter barrels-as was its predecessor.

Note that in these articles I’ve also cited contacts in the industry who claim that this concern is a bit overblown, and that a barrel twist of 1:9 is perfectly sufficient to stabilize bullets up to and including 62 and 65 grains, and even 77 and 80 grains. Some of this has to do with barrel manufacturing procedures and quality.

I think Andrew just confirms what we already knew.