Tag Archives: reliability of AR-15

More (Sort of) Deep Thoughts About Guns (gas operation, AR-15, Rem 1100, 38 Super, headspacing)

26 Oct

In the book, I talk about the basic operation of semiautomatic pistols. The new edition will talk a bit about the basic operation of semiautomatic gas-operated rifles too. Why? Because understanding the basic operation can help us maintain our weapons and use them most effectively.

Gas-operated weapons, by their nature, are more particular to the ammunition used and can be more dependent upon proper maintenance.

At the simplest level, gas-operated weapons work as follows: There is a tiny hole in the barrel, called a gas port. When a bullet passes this gas port, the expanding gasses behind the bullet push into this gas port. This energy is used to cycle the action.

Some weapons use a piston or operating rod which is pushed back by the gasses. This rod or “slide” or piston operates the bolt. Weapons based on the basic M1 rifle design do this. Other weapons might feed the gases back to directly operate a bolt. [To demonstrate how this works with a diagram, I tried to find a webpage that contains figure 2.11 from an older book I have titled Basic Gunsmithing by John E. Traister. It’s a cutaway of the side of a Ruger Mini-14. Alas, I didn’t find it online. It’s an older book, published in 1979.]

One thing becomes clear. You need to keep the gas port free of fouling. If gases can’t get through that hole, your gun won’t function reliably. Because burning powder residue can get on other moving components too, it’s important to learn to properly clean your gas-operated weapons. Different weapons will need different levels of attention.

Two guns that come to mind are the M-16 and the Remington 1100 shotgun. I think of these two guns together, because each has a mixed reputation. Ask some people about the Remington 1100, and they’ll say they’re not reliable. Others swear by them. Same is true of the AR-15s. Some say they have reliability problems. Others say they’re great.

What explains the difference? In the Remington 1100’s case, it all comes down to cleaning. You must learn how to properly clean the gun, including the gas port. If you’re unsure of how to disassemble and clean some gun, my suggestion is to search Youtube.

For the Remington 1100, I found this nice presentation on Youtube:

(disassembly)


(part 1)


(part 2)

Youtube rocks. Watching the videos, you’ll notice the rubber o-ring seal on the shotgun. Many years ago, when I first learned that some guns had rubber O-rings and other rubber parts, it blew my mind. Still does, kinda. [I’m still waiting for Ruger to send me a metal trigger for my Ruger Standard Pistol from the 1970s. A plastic trigger must have been a mistake. Right? It was like a template for making the real trigger or something?]

If you’re trying to seal in gasses, and something isn’t working and rubber O-rings are involved, try replacing the O-ring. A prepper can never have too many O-rings. (Well, OK, I guess you can have too many.)

The Remington 1100, with a bit of care and cleaning, can be a great weapon for the prepper. Many recoil-sensitive shooters and skeet and trap shooters love gas-operated shotguns because they reduce felt recoil appreciably. For a smaller, recoil-sensitive person, a gas-operated 20 gauge shotgun is perfect.

In the case of the M-16, one of the factors that led to reliability issues had to do with the gunpowder used. A slower-burning gunpowder was substituted without adequate testing. A slower-burning gunpowder creates more pressure at the gas port, which leads to a more aggressive cycling of the action. In the case of the M-16s, this effect was so pronounced that part of the cartridge case’s rim was ripped away sometimes.

This doesn’t affect reliability of the AR-15s today. Here’s a good article for those who want to learn more. Whenever one group of people says something doesn’t work, but a huge group of others say it does, look at how each group is going about doing the thing in question. You’ll often find success is attributed to some simple thing.

If you want to learn about cleaning an AR-15, here’s a nice video:


http://www.youtube.com/watch?v=PXEW0YkxgWE

murpheysmuskets (on Youtube) has a nice comparison of the DI AR-15 system versus the M1 or M1A gas systems:


http://www.youtube.com/watch?v=HmSG7mtAX7U

Here’s a short video about some spare parts you might want for an AR-15:

While some old-schoolers look down on the AR-15, a recent post about the 1911 pistols made an interesting point. The poster said that older 1911 weapons weren’t reliable because the three finger bushings broke (sorry I didn’t save the link). That doesn’t apply to 1911s today because they all use solid bushings. So even legendary gun designer John Browning didn’t always do everything perfectly from the start. It just shows there’s always some room for improvement and refinement. We shouldn’t hold a weapon’s early history against its modern incarnation.

Another great example of a weapon besmirched by its early history was the 38 Super. This had the potential to be a great pistol caliber, but was done in by a bit of bad design. Some shooters are familiar with the concept of headspacing. It often reduces to a length measurement. Physically, we can think of headspacing as what keeps a cartridge casing from moving forward in the chamber. If a cartridge moves too far forward all sorts of bad things can happen, like the casing blowing apart.

There are several ways of headspacing. Many calibers have a rim. The casing can’t move too far into the chamber because the rim retains it. The 357 magnum, 44 magnum, 30-30 WCF, and 22 LR are all cartridges with a rim. Some magnum calibers have a belt, like the 458 Winchester Magnum. Most rifle calibers headspace off of the neck. The neck of the cartridge keeps it from moving too far forward. The 308 Winchester, the 30-06, and the 223 Remington are common examples.

Some wildcatters like to neck 30-06 brass to larger sizes like a 338-06 or the famous 35 Whelen. Whelen contemplated a 40 caliber neck-up of the 30-06, but deemed it wasn’t a good idea. There was so little neck left that the round would be inherently dangerous. The weapon might not headspace reliably. The case would jam itself deeply into the chamber, the brass would rupture and ka-boom, in a bad way. [the contrary opinion about the safety of necking a 30-06 to 40 caliber]

Modern autoloading pistol calibers almost always headspace off the case mouth. This means the lip of the case prevents its forward movement of a fired cartridge. [this is difficult to believe for many, myself partly included. What happens if a bullet is crimped too much? Some claim it’s actually the extractor holding the case back in most autoloading pistols. I don’t believe that either!]

The 38 super had the unfortunate lineage of having a semi-rim and trying to headspace from that. It didn’t work too well. Worse, misguided attempts to handload the 38 Super hot contributed to the problem.

This isn’t a problem with modern 38 Super barrels which headspace from the case mouth, just like the 9mm or the 45 ACP. It’s a shame the 38 Super didn’t begin life with headspacing from the case mouth. If it had, it might well be the most popular autoloading pistol caliber today.

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Many preppers recognize water as the most vital resource. Here’s a great article about water. Before clicking through, here are two questions to ponder: 1) Given the modern American life, how much water is needed daily for each American? Don’t just include water for drinking, washing, and cooking, but consider the water that is used for things like generating electricity and raising livestock. 2) How many gallons of water go into producing one pound of beef?

Here’s another interesting article about water.
About one-fifth of California’s energy use is to pipe water from one place to another.

A piece about divvying up the water from the Colorado River.
Stein’s Law: “If something cannot go on forever, it will stop.”