AR-15 Weight and Balance

On the internet, the debate rages on.

What is the debate? Well, it doesn’t really matter. People will seemingly argue over anything – and I’ve been guilty of that myself.

One of the more popular debates is weight. Proponents of lightweight rifles point to carbine courses where a heavy rifle can get tiring, and accessories that boost the weight of the rifle, meaning that starting with a lightweight carbine is better. Proponents of heavy rifles say that they work out a lot, and their grandfather carried a BAR while assaulting the beach at Versailles, so weight isn’t a problem.

Another topic is balance, and this is a term that I have yet to see defined by a majority opinion. Some people like the weight to be on the front of the rifle. They load up their rail system with lights, VFGs, bipods, etc, over a heavy barrel profile, and with a standard or lightweight aftermarket stock out back. Others like a rear bias – they’ll get a Magpul UBR and stick it on a lightweight rifle with a pencil barrel and a pistol light on the handguard. Finally, some prefer a neutral balance – like myself (although I do prefer a very slight rear weight bias).

Before I dive into the meat of the issue, I’ll define something. Center of gravity (CG) – and if you’re a pilot, you’ll know what I’m talking about before I say it – is the point at which something will balance if it were suspended from that point. This is easier said than done, but with the AR-15, I’ve given it my best effort.

With an airplane, fuel is normally located at a point near the center of gravity, so that the flight characteristics of the airplane do not drastically change from the beginning to the end of the flight. Similarly, the cartridges in an AR-15 magazine are located at a point which is essentially right on the center of gravity of a stock M4 carbine. Thus, as the ammunition is expended, the balance of the rifle does not really change. What this means is that whether you’re firing the first round or the thirtieth, you won’t have to compensate as you bring the rifle up to a firing position.

With a CAR stock, CAR handguards, and the A2 flash hider, the weapon's CG is right at the point of suspension.This is my definition of a "neutral" CG for the AR-15.
This rifle weighs almost 2lbs more, but has a nearly identical center of gravity. How? Properly balancing the weight of accessories up front with a heavier stock at the rear.

You may not notice it without someone telling you to look for it, but if you have a forward weight bias – meaning that you’ve moved the center of gravity forward from the “stock” position – as you expend ammunition, the weapon will become slightly more nose heavy, because weight is being reduced at a point behind the CG, thereby shifting it forward.

Whether you have two rifles or twenty, maintaining a consistent center of gravity will help you shoot better when switching from weapon to weapon. Incidentally, when starting out on this project, I discovered that all of my AR-15s had almost exactly the same center of gravity, although weight varied as much as 4 pounds from lightest to heaviest.

Now, aircraft CG does not directly relate to weapon CG, because you’re putting different forces on a rifle while shooting it than you would on an airplane by flying it, but the basic principles remain the same. Furthermore, I won’t go into the details of aircraft weight and balance – weight, arm, moment and all that jazz – but I will explain what you need to know to fine tune the balance of your AR-15 to something that might be more agreeable to you.

First, understand that the closer the weight is to the center of gravity, the less effect it will have on the location of the CG. To demonstrate this fact, observe the following pictures.

Here, an A2 flash hider is exchanged for a Smith Vortex flash hider. The weight difference is .05lbs.

A tiny change in the attitude of the weapon. Now, watch as a magazine is inserted:

The only change made was the addition of a Magpul PMag with 28 rounds of 75gr ammunition – because the suspension point was slightly forward of the CG (note the muzzle high attitude), there was a tiny change in the attitude of the weapon. That magazine weighed 1.2lbs on a postal scale.

From this, we see that adding weight close to or on the center of gravity will have little effect on the balance of the weapon compared to adding weight farther away from the CG. Because I like to put my optics right at that natural CG, it doesn’t matter whether I have an Aimpoint or EOTech or even a 1-4 variable – the balance of the weapon will basically be unaffected.

Now, let’s see how other parts changes affect balance.

Adding a KAC M4 RAS, rail panels, and a stubby VFG shifted the weight forward slightly. Alone, the M4 RAS was, at .55lbs, .25lbs heavier than the CAR handguards and .15lbs heavier than MOE handguards; with panels and a VFG it weighed .85lbs.

The addition of a Vltor EMod stock shifted the weight to the rear significantly. This is because the CG of the EMod itself is way at the rear of the stock – so even though it doesn’t add much weight to the rifle in an overall sense, it does have more of an effect on CG than other stocks. In other words, if you want to balance out a front-heavy carbine without making the weapon a lot heavier, the EMod is for you. Some applications may still call for a heavier stock, though.

Swapping a rail panel (.05lbs) for a Surefire X300 (.25lbs) brings the nose down slightly…

The additional .05lbs of a Surefire G2 and polymer mount (.3lbs) bring the nose down just a little more (note: a metal head and metal “clicky” tailcap will add .05lbs each)

Finally, the .6lbs of a Surefire 9P in a Vltor offset mount bring the CG back to “neutral”, almost.

I brought another rifle and tested it (without optics) – with a VCAS sling utilizing QD swivels, the rifle was neutral…

Without the sling and the swivel at the rear of the stock, the nose of the rifle dipped a little. The forward swivel was mounted at the rear of the rail, so it had little effect on the CG. Yes, this rifle had a Daniel Defense M4 12.0 rail, Surefire G2 LED, Magpul MBUS front sight, several rail panels, and a stubby VFG. How did it balance almost the same as the other 16″ M4 profile rifle with an EMod in the same position? Well, the Vltor low profile gas block is much lighter than the standard FSB, the QD socket at the rear of the rifle helped, and the PWS FSC556 is a tad lighter than the Smith Vortex. Those minor changes allow me to drive the rifle with a “better” VFG position and increase the sight radius without significantly affecting the balance of the weapon.

You may be getting the impression that these changes aren’t making a very big difference. However, if I installed a RAS, VFG, light, etc and left a CAR stock at the rear, the muzzle device would practically be on the ground. Every change I made was very slight and designed to have a small effect on the overall balance of the weapon. I’d also like to note that the collapsible stocks were set at comfortable shooting positions for me – your stock usage may vary, and you should balance your rifle accordingly.

ith a CAR stock and the A2 flash hider, the weapon’s CG is right at the point of suspension.

Cammenga EasyMag

If you’ve been using magazine fed weapons for a while, you’ve probably loaded quite a few magazines. Steel and aluminum AR-15 magazines are not very well known for being easy to load, and while mag loaders are available, I’ve never felt the need for one – I’ve just sucked it up and loaded mags the hard way.

This product isn’t new, but it does address this issue in a unique way. The Cammenga EasyMag, which is produced in Michigan, features a “sliding body” design that allows the user to slide the mag open, simply drop rounds into the magazine, and then slide the mag closed. At that point, the mag is ready to go. If your fingers and thumbs don’t have a whole lot of strength, this may be a good option for you. As an aside, it can be loaded and unloaded just like a standard magazine, and it’s remarkably easy to do so.

However, it’s not without drawbacks. In order to slide the magazine open, you have to have a certain amount of grip strength – I handed the mag over to the rangemaster, who is in his 60s, and he was unable to get the magazine open. Also, there are a number of sharp edges which can slice you if you’re not careful. If you don’t load 30 rounds in the mag, or close to it, it may spit out one or two rounds when the follower slams upward. I’ve found that keeping my palm at the top of the mag when closing it will prevent any rounds from flying out. Finally, rounds may slide out the back of the mag when you’re loading #28-30, so it’s best to load two rounds at a time, essentially side by side.

Now, on to function. I’ve destroyed my share of magazines in drop and crush tests, but it wouldn’t make sense to do so without ensuring that the magazine works before anything bad happens to it.

I loaded the magazine with 30 rounds of Silver Bear 62gr HP. Previously, I had fired about 150 rounds of this ammunition through the rifle (Spike’s Tactical CHF upper, Sun Devil lower) without a hitch, using several different types of magazines. The magazine was fairly easy to insert with 30 rounds in the mag and the bolt forward.

The first round fed out of the magazine just fine, but the second didn’t come out of the mag. Here’s a picture of an identical stoppage that I encountered with different ammunition. In over 1500 rounds and with a variety of magazines and ammunition, this weapon has never suffered any kind of stoppage – until now.

Interestingly, tap rack bang didn’t work with this magazine – not at all. In order to rap the bottom of the mag hard enough to have any effect on the follower or the rounds in the mag, I had to remove the mag from the weapon and slam it down on one of the tables at the range. Later, I was able to hit the bottom of the mag with the heel of my hand about a dozen times, and the malfunction was corrected.

The rangemaster and I then fired the remaining 28 rounds without any problems, however, the bolt did not lock back.

I then fired 10 more rounds of Silver Bear, the last I had brought. The bolt locked back, and continued to do so for the rest of my range session.

At that point, I was out of Silver Bear. I had loaded 100 rounds of 55gr .223, so I switched to that. I fired 5 rounds from a loaded mag of 30 to ensure function, then replaced those 5 rounds, and dropped it on asphalt, directly on the feed lips, from chest height – as if I had fumbled a reload. Here’s what the mag looked like.

Other than a few scratches, the magazine looked just fine. I loaded and made ready, and fired the first round. I could feel that the bolt had gone forward, so I squeezed the trigger again…click! I dropped the mag, and here’s what I saw.

Again, tapping the bottom of the mag didn’t work – I had to slam it on the table.

I was then able to fire the rest of that magazine without and problems.

I loaded and dropped the mag three more times, firing 5 to 10 rounds after each drop, then replenishing the magazine. During one of these strings of fire, I encountered another FTF, which is pictured above.

While it didn’t spit out any rounds during the four drops – which is very rare, in my experience – it did cause the rounds to stick out of the mag at odd angles. These problems were relatively easy to fix with finger pressure.

After the fourth drop, I noticed a crack forming at the rear of the right feed lip, on a spot weld.

At this point, I stopped drop testing, and fired the remaining ammunition without any problems.

After I had expended the 140 rounds used for testing, I opened and closed the mag a few times to see if it had gotten any easier to do so. I don’t think that it had, but on one of the cycles, I “over-closed” the mag, and this was the result.

It was pretty easy to slide back into place, and I was unable to repeat that issue, but it was interesting nonetheless.

In my opinion, a magazine has one purpose: to work. If it doesn’t work, it’s not useful. While this mag has many good points – the strength of its spring steel body, for example – the simple fact that I encountered so many stoppages and issues means that I wouldn’t use it outside of the training arena. Even if it had functioned perfectly, I’m not convinced that it is very useful for folks with bad joints or weak hands, because it does require a good amount of force to open, although closing the mag is easier. It would certainly be beneficial for those who have to continually load mags over and over and over, such as in a carbine course – but for patrol, duty or combat, magazines should be loaded prior to use, even if that takes a few extra minutes to load the “old way”.

My standard disclaimer: I was provided with this magazine, free of charge, for test and evaluation purposes, by someone connected with Cammenga.

This Just In: “Climate Change” Data is Being Faked

As you can see on this blog, some unknown hacker has done the world a favor by releasing emails and internal memos, among other documents, from a group that receives money from several world governments to do climate change research.

I won’t bother copying what the other blogger reported, but here’s a nice quote from one of the emails:

“I’ve just completed Mike’s Nature trick of adding in the real temps
to each series for the last 20 years (ie from 1981 onwards) amd from
1961 for Keith’s to hide the decline.”

Good to know that they were being honest, eh? As if many people didn’t already know that “global warming” is akin to looking at two seconds worth of temperature data from one thermometer located in direct sunlight, they have to falsify data, too? This, and the earlier debunking of the famous tree ring data, should give any thinking person pause before supporting “climate change legislation”.

Something to think about, also from the file:

“The fact is that we can’t account for the lack of warming at
the moment and it is a travesty that we can’t. The CERES data
published in the August BAMS 09 supplement on 2008 shows there
should be even more warming: but the data are surely wrong.”

Upcoming tests/reviews…

I haven’t posted anything in over a week, as I’ve been pretty busy. However, I’ve stayed on top of certain things. In the next few weeks I’ll be doing .30 caliber AP projectiles vs. multi-hit Level IV plates – in accordance with NIJ test standards, or as much as I can realistically comply with them.

Testing – Cammenga magazine testing, and more AR-15 dirt testing, including starting with the bolt locked to the rear.

Gear – a “war belt” write up, and a more extensive review of an ALICE-frame compatible pack, made by the quality gear maker HSGI, that I’ve been using for quite a while.

I’ll also be talking about some interesting wildcat cartridges for the AR-15 platform, including a .30-caliber wildcat that uses standard 5.56 magazines, bolts, and brass, while exceeding the supersonic performance of .300 Whisper. For someone looking to stretch their AR-15’s performance on a budget, especially for hunting or self-defense purposes, this may be just the ticket.

If you have 10 minutes to spare, watch this video.

Every month, MDTS puts out a short video. They’ve had good things to say in the other videos I’ve watched, but this month’s video will help just about anyone.

I’ve tried to get across similar points in my blog posts – mainly, avoid confrontation whenever possible, and pay attention to your surroundings – but this is an excellent description of a thought process that might one day save your life.

A.R.M.S. Throw Levers – Not Exactly Perfect

As some folks have learned the hard way, A.R.M.S. throw levers sometimes fail at inopportune moments.

LaRue mounts, on the other hand, are well known for their return to zero qualities and toughness.

In this video, I demonstrate the difference between the two.

The A.R.M.S. throw lever fails after four hits, while the LaRue is damaged, but still fully functional.

The sad part is, a lot of companies get suckered in to using A.R.M.S. mounts for their products – such as the EOTech 553 and Elcan Specter DR – when far superior mounts are available.

LaRue isn’t the only game in town – I like Bobro and American Defense as well – but A.R.M.S. shouldn’t be on anyone’s purchase list.

It should be noted that I have no connection with either company, and procured both mounts shown in the video with my own funds.

A False Sense of Security

We’ve all seen the Brinks home security ads. Now, they’re operating as Broadview Security – but the ads remain the same. Here’s an example.

There are a lot of illogical things in the video – one of the biggest things that stands out to me is the fact that the criminal is brazen enough to kick in a door in the middle of the day, while people are at home – whether you’re in the backyard or not, that type of criminal isn’t going to run away when they hear an alarm.

They will run away when they hear something else, though – gunfire. Don’t believe me? Check out this video. Four men, armed with an AR-15 and several handguns – and they can’t pull up their pants fast enough to keep themselves from tripping as they scramble away.

But that was an isolated incident, you say. When the alarm goes off, the company immediately calls you, and a smart-looking guy in a room resembling the CIC (Combat Information Center) of a US Navy aircraft carrier “sends someone right away.”

Well, what does “right away” mean? And who are they sending?

Well, the police will respond to alarms. However, due to the exceptionally high number of false alarms, police response times to alarms are normally upwards of 30 minutes, and in some cases, several hours. Some departments require that alarm companies verify that the alarm isn’t false before responding.

So in most cases, the response that companies advertise is someone who passed a drug test, has a GED, and hopefully knows which way to point his weapon – if he’s armed at all. There are a lot of proficient security guards, but they’re hopelessly outnumbered.

As for the response times of these security guards, Broadview won’t elaborate beyond saying that it’s “rapid”. They also don’t offer any information about the people who respond to alarms. Most of their “success stories” are simply people who pushed the “send help” button when a fire or medical emergency occurred. While this is certainly a nice feature, they still call you to verify that you need help, so you might as well have cut out the middleman and simply dialed 911.

Another thing I noticed about the video – actually, most of their videos – was that the bad guy gains entry simply by kicking in the front door. Why go to the trouble of having an alarm installed if you’re going to have a front door that can be opened by one solid kick from an adult male? If it was that simple all the time, SWAT teams wouldn’t have large, heavy, and expensive breaching tools which they use to gain entry to various buildings. A good, solid door – better yet, a metal security door which swings outward, but has hinges that aren’t exposed – and some good deadbolts will keep some random guy in a hoodie from kicking in your front door.

Here’s my favorite ad. It’s from the Brinks days. In this scenario, the wife tells the husband to go “check out a noise” – and the husband wanders off in the dark, weaponless, without a flashlight, and without turning on any of the lights in the house. Quite frankly, that’s a good way to get killed. The husband sees the bad guy and immediately runs away, slamming the bedroom door behind him. Well, if the front door didn’t stop the intruder, why would a hollow core interior door stop him? Of course, the alarm system “scares off” the bad guy. The alarm company guy sends someone (presumably, someone with balls) “right away”. The day is saved.

Now, I’m not saying that you should never get an alarm – they’re certainly nice for when you’re away from home. An alarm would be a good component of a complete home security plan – a fire safe for valuables and firearms, motion detector lights covering the outside of the house, good locks on the exterior doors, a dog, possibly even security cameras, etc – but if you’re relying on the alarm alone, you’re not doing yourself any favors.

Barrel Factors for Small Arms

Today I received, by email, an interesting paper - from 1968 – which discusses DOD testing regarding materials to be used in the making of barrels for small arms. Before I go too far, we have to understand what a “small arm” is. To the military, this can be something which is quite a bit larger than what a civilian might encounter at a gun store or shooting range. This report was done at the request of the Air Force, which was interested in improved materials for minigun barrels up to 30mm. However, if a material is found to be suitable for use as a 30mm minigun barrel (and the miniguns referenced in this paper can fire 100 rounds per second through their six rotating barrels), it will probably be suitable for use in a semi-automatic rifle firing 5.56mm or 7.62mm ammunition.

The paper is difficult to read, for it appears to be a copy of a copy of a copy. However, what is legible is pretty interesting, if you’re a gun buff like me. If you want to learn technical stuff about barrels and how they wear, read the first few pages.

Some interesting highlights include:

– Titanium, and titanium alloys, displayed significant wear after a single round was fired.

– Chrome moly vanadium barrels which were chrome lined offer greater wear resistance over barrels that were nitrided (also known as Melonite, Tenifer, etc). This is relevant to folks who are considering a new AR-15 upper or barrel – nitriding comes at a lower price and does extend barrel life compared to a bare steel barrel, but it’s not the equal of chrome lining when considered from a barrel life standpoint. It may offer other benefits, such as a slight increase in accuracy, but that wasn’t part of the study. As we see in this study, nitrided CMV barrels, when used in a machine gun firing 200 rounds per minute, will last up to 30,000 rounds, while bare steel barrels lasted on average under 10,000 rounds.

– Chrome moly vanadium barrels with Stellite 21 liners that were then chrome lined set the standard for wear resistance.

Another study to read if you want to learn about barrel material, rate of fire, and barrel contour as they relate to machine guns – in this case, M60s and .30 caliber Brownings – is this 1974 paper. The major lesson to be learned is one that most folks already know – lighter barrels, though nice from a weight standpoint, will die faster than heavy barrels when shot for extended periods of time. We also see this in a destructive test of the (heavy barrel) M4A1 versus the (lighter barrel profile) M16A2 – although both barrels failed at approximately 1600F, it took longer for the M4A1 to reach that temperature.

And finally, if you’re an environmentalist who loves cannons, there’ something for you, too.

It’s going to be a bumpy night…

…actually, it’s going to be a bumpy year.

I’ve no doubt that the Democrats will lose big in 2010 – and any chance for the Pelosi/Reid/Obama machine to “change” our country will be gone at that point.

But who will take their place? And what will they be able to accomplish in the meantime?

Edit: They know it, too. President Obama made reference to “casting a vote that might lose an election for you” when he addressed House Democrats. Translation: They know the end is coming – soon – and I believe we will see more legislation such as this come before Congress. That is, radical legislation which has no basis in the Constitution and turns America into just another socialist state.

“Gun Free Zones”

Today our nation mourns the loss of 13 warriors, and prays that the dozens in hospital will recover fully, although the sad reality is that many will be damaged for life, both physically and mentally.

We have not yet heard renewed calls for tighter gun laws, although with the inevitable copycat shootings that are sure to follow, we probably will.

What most gun control advocates conveniently ignore is that the majority of mass shootings take place in “gun free zones” – shopping malls, schools, businesses, and in this case, a military base. Under most state laws, if a business clearly states that firearms are not allowed, it’s illegal to have a firearm there. It’s also illegal to discharge a firearm within city limits, it’s illegal to brandish a firearm, and it’s illegal to commit murder.

And yet we still have mass shootings. What is the answer?

Here is the fundamental difference between people such as myself and people who want tighter gun laws.

I believe that the answer is more personal responsibility – more people looking out for themselves. Gun control advocates want the government to take care of us as much as possible. They want more laws and more regulations. I want fewer laws and fewer regulations. I want more trained citizens to be able to carry, more of the time.

Lawful concealed carry in the United States has not resulted in the streets “running red with blood” as anti-gun folks predicted. Citizens who take the time to go through the concealed carry permit process are not a threat to civilized society.

The simple fact is that you could never remove all firearms from the United States, and no matter what smokescreens are put forth about preserving the “American hunting tradition”, this is the ultimate goal of gun control advocates. Some people will never give up their guns, and some people will always be able to find them. In the UK, police officers didn’t have to be armed until after practically all firearms were banned – now, London police officers are arming themselves with submachine guns.

The hard lesson of these incidents is that active shooters will not stop until they are neutralized with gunfire. We will keep learning that even brave and well-trained police officers such as Officer Kimberly Munley cannot be everywhere, and by the time they are able to respond, dozens may be dead or dying.

In an event such as this, a law will not protect you. A ban on “high capacity” magazines won’t protect you. Police officers may be unable to protect you. The only person who you will always be able to rely on for protection is yourself.