Part 3: (Direct Gas Impingement (DI/DGI) vs. Gas Piston Operated) Some of the problems that plague the classic AR style rifle platform have to do with reliability, especially in sandy and dusty environments, as evidenced in Iraq and Afghanistan.
This article is Part 3 in a series of posts.
Read Part 1: (A Little Background)
Read Part 2: (History)
There’s nothing worse than having a survival tool fail on you when you need it most and the two loudest sounds in the world are: a “click” when you expect to hear a “bang”, and a “bang” when you expect to hear a “click”.
The military and the gun industry have been looking to fix the problems associated with the reliability of the M4 carbine’s direct gas impingement system (DI/DGI) and one of the options that has risen to the top of the stack is the gas piston operated alternative. This is a very controversial topic and there are many that believe the DI/DGI is still the best option and the gas piston system introduces a whole new set of problems.
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The question remains, what would be the best AR survival rifle choice. Before we get into brands, let’s look at some of the new AR gas piston rifle systems vs. the classic AR legacy rifle, direct impingement systems. One of the first factors to consider is the compatibility of parts between different AR systems.
It’s important to consider the high likelihood that if you use your rifle system, at some point something may break and need to be replaced. The fact that the new gas piston systems do not enjoy total parts compatibility between brands and that there are currently fewer on the market compared to the legacy DI systems, may outweigh many of the performance considerations when choosing your primary survival rifle.
For a look at a mechanical and performance demonstrations of each type of system, please look at the following illustration of mechanics provided by the Army Times.
HK 416 (Gas Piston) vs. Colt M4 Carbine (Direct Impingement)
There are a couple of great reference handbooks on each of the systems written by Mike Pannone as well and are worth checking out.
HK-416 Handbook
M16/M4 Handbook
Let’s look at the differences (Pros and Cons) between a direct gas impingement operated and the gas piston operated rifle.
Gas Piston
Pros:
1. Run cleaner
2. Run cooler (can contribute to longer life and less breakage due to heat and wear)
3. Run (arguably) more reliably than DI/DGI systems especially when chambered with 5.56 mm NATO in SBR (Short Barrel Receivers) and running cans (suppressor/silencer).
4. Typically need less lubrication to run reliably which means they don’t pick up as much grit and run cleaner especially in dirty and dusty environments (see #1).
5. Can reportedly run a wider range of ammunition with less finicky results than a DI/DGI system.
6. Usually, everything not directly related to the proprietary piston system is MIL-SPEC and interchangeable with its DI/DGI brethren. Brand specific on whether this is standard but most of the top manufacturers seem to have this quality in common.
Cons:
1. Possible Carrier Tilt Wear – The piston places torque on the gas key causing the back of the 
carrier to tilt down causing scrapes along the buffer tube and shearing gas keys. The original AR platform was designed as a free floating bolt carrier. Some companies have addressed this (i.e. LWRC) by installing carrier guide rails and going to solid one piece carriers and/or upgrading the buffer (i.e. PWS enhanced buffer tube) as well as some other proprietary fixes.
2. Usually heavier than DI/DGI systems (for example HK reportedly had to thicken their barrel in the HK-416 to counteract barrel flex caused by the forces exerted by the offset, reciprocating gas piston and operating rod. This system was already much heavier than its DI/DGI competitors)
3. Many parts are proprietary and unable to be changed out easily at the user level (i.e. the rifle has to be sent back in to the company to undergo barrel changes or repair/replacement on proprietary parts)
Direct Gas Impingement (DI/DGI)
Pros:
1. Typically lighter
2. Some claim they are more accurate (other arguments are that the barrel is the deciding factor in accuracy not the DI/DGI vs. Piston system).
3. Enjoy more interchangeability with currently fielded military equivalents (especially when dealing with MIL-SPEC AR systems) this means replacement parts are more readily available and if you buy a certain brand of AR, even if the particular company goes out of business, you can turn around and acquire compatible parts from any number of other companies.
4. Easy and quick shooter level maintenance and parts upgrades/changes, which means you usually don’t have to send your rifle back in to the shop. In a TEOTWAWKI or a long term survival situation… you aren’t going to be sending anything to the shop… you have what you have or what you can find along the way and that’s it. If it stops working and you can’t fix it… it’s dead weight, especially if you are on the move.
5. Easy to build your own franken-rifle/M4-gery from the ground up using the wide variety and compatibility of AR parts available on the market from numerous manufacturers.
Cons:
1. Usually runs very dirty due to its gases being blown back into the chamber which is what makes the rifle cycle. This system is often described as one that Sh*ts on itself.
2. Reliability when running SBR’s/Short Barrel Receiver (especially barrels shorter than 12.5”), suppressors or in very dusty sandy conditions (i.e. during a sandstorm reliability test the M4 was prone to jamming 3.5x more than the 3rd place finisher. ref link: here).
3. Require more maintenance and cleaning.
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These are all important considerations to take in before buying or upgrading your Survival Carbine. There are a lot of gun manufacturers out there and most of them make a pretty good product but as you well know, sometimes you get what you pay for. It is worth noting that the AK-47 is a gas piston driven system and no one has ever questioned the reliability of that weapon system.
Continue Reading Part 4: Build Options
In the next installment we’ll look at some of the survival carbine (AR style rifle) choices from some currently available brands, both in DI/DGI and gas piston systems.
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Although an M4/M16 system is more likely to jam, most of those jams can be avoided as long as you take care of it as needed. I am active duty Army, and many of you vets can back me up here, weapon maintenance is key to an M16. Just food for thought. As long as you are trained in how to clean it, reliability isn't a huge problem on an M16.
I agree maintenance, cleaning, descent ammo go a long way, not to mention always have a back up. Besides, 800 out of 60,000 is less than 2% not bad.
But what happens when you dont have time to clean it your on the move and cant spare the time. I know many would say that you make time but i find that hard to justify if my family and i are being chased by looters or some suck to say "we need to stop i got to clean my AR again".
Are there pack mules following you carrying ammunition too? Because you can't carry enough to make the thing dirty enough to jam when it's clean. This BCM M4 test went over 2400 hundred rounds with no oil and no cleaning before it had a problem. He says many times he gets over 4000.
http://www.defensereview.com/the-big-m4-myth-foul…
PART 3?! REALLY?! ARE WE SERIOUSLY STILL GOING OVER THIS? AND NEXT WHERE GOING TO BUILD ONE? AFTER THAT CAN WE SIT NEXT TO THE CAMP FIRE AND SHARE STORIES ABOUT HOW THIS WEAPONS SYSTEM HAS COST MANY AMERICANS THERE LIVES!
AR'S ARE A VERY A VERY LIMITED WEAPON AND THEREFORE SHOULD BE USED IN LIMITED SITUATIONS! YES YOU SHOULD SHOOT WHAT YOUR COMFORTABLE WITH OR WHAT YOU CAN GET YOUR HANDS ON BUT IF YOU CHOOSE AN AR FOR YOUR MAIN WEAPON YOU BETTER LOVE SHOOTING FROM THE PRONE BECAUSE YOULL END UP IN A PINE BOX! JUST ASK MY FELLOW SOLDIERS AND THE THOUSANDS BEFORE THEM THAT LOST THERE LIVES TRYING TO MAKE THIS WEAPON SYSTEM "WORK".
THIS AR BS HAS FINALLY GOTTEN TO ME………………………………………
Yup. The AR jams a lot. Yup, 7.62 rounds are heavy. Shoot what you like. But my AR can shoot .22, 5.45, 5.56, .308 and 50BMG (ooops, forgot 50 Beowolf).
And: 5.45 is 11 cents a round on aimsurplus!!!!!!! Wahooooo!!!!
Too loud, chief… you're missing the forest because all the trees seem to be obstructing your vision…
Having served in the desert of Iraq with 108 of the finest men and women I have ever know and having EVERY one of them return home was more than anyone could hope for. Guess what weapon system we carried. M16s. I have not heard of issues with the weapon system in current configurations where American lives were lost due to malfunctions. If you have been around semi auto and full auto weapons much you KNOW the majority of malfunctions are caused by cheap and poorly made magazines.
I have to agree with Michael about the utility of bikes. First off while you are sitting in Bugging out traffic my bike will be breezing by nicely in between the cars. Also a number of trailers will carry pretty easily more than 50 pounds of stuff. The local bike co-op where i live a a number built especially for things like firewood which work great.
You also have to think about. How am I going to keep this running? Sure the gas issue is easily prey, but what about more serious issues. If your vehicle breaks down are you going to have all the tools and parts you need to keep it running? Do you really know how to fix everything on your vehicle with the tools at hand? I can keep all the tools and most prone to failure spare parts for a bike in a fanny pack. Not to mention it is easy to find bikes just laying around or in abandoned garages giving me a huge pool of spare parts to choose from that are easily salvaged. I can hide it with almost no effort and how many other items have people suggested are able to be carried by hand easily over an obstacle? and once i get to my bug in locale i can prop it up on a pedal-power generator and charge all my electrical equipment without need of anything more than a power bar and some h2o.
Hi guys! New here and was just wondering – when it comes to us foreigners, not necessarily living in a very gun-friendly country, what kind of defense-plan would you suggest? (…that is; not involving firearms)
I suppose a blade would be the most obvious answer, but I'm just checking to see if anyone's got any ideas!
//Sweden
That is a good question and also points out something a great deal of Americans are guilty of; a lot of us rely on firearms too much. Be assured that when the SHTF in the US we will see a lot more guns used in crime and therefore must use our guns to defeat a threat. In Sweden one will not encounter firearms as much as the US but to have an advantage you may want to look at tomahawks or the Cold Steel Spetznas shovel. Knives are great but an ax, tomahawk or shorthandled shovel has destructive power beyond that of a knife in some cases. Also you may want to take up martial arts or self defense and keep your body in good shape. Good luck over there and God bless
Slightly off topic, but a good question. You might want to consider getting yourself a cane or a walking stick and then training in a martial art that has jo (short staff) and bo (quarterstaff) techniques. The short staff techniques might be preferable as few people would see a cane as something too far out of the ordinary. I don't know about the laws in your country, but here (U.S.) if you a draw a knife that's automatically considered to be deadly force. A cane or a walking stick not so much. Besides, as you're walking down the street with your cane, your "weapon" is already "drawn". You also have a significant reach advantage over somebody with a knife.
My general advice would be to try to steer clear of knife vs knife fights unless you have no other choice. If concealability is not an overriding factor, go for a bigger knife [see the movie "Crocodile Dundee"
] with a blade length somewhere between 9" (23 cm) to 12" (30 cm).
Yeah, I figured. However I couldn't find any article on the subject, so I thought I'd just post the question in the comment field.
The law is pretty much the same here, and if I remember correctly, there are laws related to knifes as well. The simple act of carrying a knife, when not in a workplace requiring one, is a crime! Although I'm not sure what the law says about bigger blades (blades obviously not made for cutting boxes, if you see what I mean) – but if I know the Swedish nanny-government well enough, it is probably illegal as well.
Thanks for the tip, I'll look it up!
Anyone else?
I really like that some attention has been paid to food prep, it is so often overlooked or simply MRE centered. My problem however is that this list overlooks some very basic rules when it comes to spices and dried herbs.
1. Powdered spices go bad way quicker that whole spices (for example, cumin seed lasts longer that cumin powder)
2. Commercially packed rubs and seasonings (ie ms dash, cajun spice ect) are mostly salt. While salt is important, too much can require greater water consumption.
3. Chili powder (like Garam Masala, curry powder, and chinese 5 spice) is actually a mixture of ground spices. The thing about chili powder is it is composed of other spices that can be kept in seed form and ground to order or used separately for different flavors. chili powder is only ever going to be chili powder. a small amount of the component spices in seed form gives you far more options and will keep longer.
4. some spices are left off that are light and go great with food that can often be foraged for in a majority of north america. Tarragon is simply the spice for mushrooms, while rosemary is great on both deer and rabbit.
5. for the long term scenario a number of spices can be grown easily. Cumin, coriander, mustard seed, and fennel can be grown in a number of climates with little effort and in the case of fennel and coriander (which comes from cilantro) you get both a spice and either a veg or herb.
Another con of the piston system is that it costs more for quality. Still, if I were using an AR for my survival carbine (I'm not-decided a newer Mini-14 fit the bill better for several reasons), I'd go with the piston version.
Two problems with the AK is that the piston is a) slightly off center and b) heavy. An "AR vs. AK" google will turn up video of this. Also see the Nutnfacny video on gas impingement vs. piston systems, he has some good points.
The average joe isn't reading this site.
Ok,some of us are worried about if the big s**t storm should happen. Can anyone tell me,if I can't afford an AR style weapon such as an M4/M16 platform. What about a Ruger mini-14? would it be capable and reliable enough? Plus as for handguns I do like the Springfield XD model in .40 and .45 caliber.
Ok,some of us are worried about if the big s**t storm should happen. Can anyone tell me,if I can't afford an AR style weapon such as an M4/M16 platform. What about a Ruger mini-14? would it be capable and reliable enough? Plus as for handguns I do like the Springfield XD model in .40 and .45 caliber.
A survival is just that. Something you use to survive until you can get to your (hopefully stashed) better weapons. It is not for full out firefights but to get you past the obstacles that are between you and them. A lot of people will laugh at my suggestions but a pistol caliber carbine such as the Hi-point 995 or the Kel-Tec sub 2000 in 9mm should do you fine to get you where you need to go. I prefer the Kel-Tec because it will take regular Glock mags. It will even take the 33 round mags. It folds in half and can fit in a briefcase or backpack with no problems. Combine that with Winchester Ranger Talon 9mm ammo and you have a pretty lethal set up to get you to your stash of better weapons. Also the Kel-Tec SU-16 series of rifles while not heavy duty combat weapons only weigh 5 pounds and take standard AR mags.
The only fighters in Afghanistan, both ours and theirs, who get hit by carbine rifle fire are the ones who by chance run into a round. Same as all the other wars in the last few decades.
If you plan on defending your retreat you might want to hit the bad guys instead of spraying rounds from a light, short noise maker.
My suggestion is to get a 30 cal hunting style auto loader. 2-3 hits from a short mag is better than spraying the sky with a 30 rounder. Think I'm wrong – them you've never had bullets zinging by your ear- or into the guy next to you.
This assumes you're shooting from inside a retreat against people approaching. Going against people already inside your dwelling or from a car against an ambush then you're probably screwed already so doesn't much matter.
With a 30 cal, you might even dissuade the MZB's to back off once they see what a 150 gr hunting bullet does to a human body.
i’m a vet of both afghanistan and iraq and the m4/m16/ar15 works fine. if you can’t hit anything with your ar15 then you certainly can’t hit anything with your .308 battle rifle. piston systems fixed some problems but with certain drawbacks. i did an experiment with my personal bushmaster ar15 and didn’t clean it for a year with moderate use. everything is stock except i had the bolt carrier group refinished in np3. i greased up the bolt and all the moving parts and it never once jammed or failed to fire or eject with moderate use. i used it in cold weather and hot weather. while i was in the military i never had my m4 jam once. learn to take care of your equipment and shoot before you buy something. and why would you be that worried anyway? if you had to bug out then that’s what you do. you aren’t going to fight 50 bad guys with you and your lone rifle anyway. you want to stay discreet and get to a position where you can build it up and have the advantage.
'stay discreet and get to a position where you can build it up'. Just so. The primary purpose of any survival weapon is not and should not be combat. It may be pressed into that role, but any survival weapon that spends more that 30 minutes in a fire fight in its lifetime probably belongs to someone who isn't going to make it. Post TSHTF, firefights are going to be short and vicious (they're all vicious if you're in it). The test of a survival weapon is 1: can it get you through the firefight (not win, just out of it alive) and 2: does it do what is needed at the BOL. I've said in many places, if we come up against trained troops, we lose. Otherwise, we make them get their heads down and GOOD as fast as possible. Then our survival weapon must do its primary job of food cultivation and pest defense.
Thank you, Finally someone says something that makes sense. All these idiots complaining about how the M4 is unreliable and ineffective probably doesn't even own one. I own five of them, and they all function flawlessly- Because I actually maintain the bastards like I'm supposed to! Let me set the record straight for all you M4 haters: The problems experienced WAY THE FUCK back during the Vietnam War were due to the first generation AR's lack of chrome-lining in their barrels. The high humidity of the southeast asian jungle caused corrosion of the bore and chamber, resulting in FTF's & FTE's (that's failure to feed and eject for all you hilljacks). Furthermore, when the first M16's were issued to troops in Vietnam, the idiots in charge of the new experiment (Project Agile) told the troops that this new weapon was "so advanced that it doesn't even need to be cleaned". Of course the fuckin' things were going to jam! I don't give a shit what weapon system we're talking about. If you don't clean it (at least once in a blue moon) it's going to malfunction, HELLO!
Mike,
Not knowing how long it takes to make the conversion (how reliable is the 'Cheap' conversion system) or how prone you might be to being unable to "unconvert" back to 5.56 I am leery of those systems. Especially in a SHTF, if your defensive carbine is in .22 mode, you don't have a 5.56 carbine, you have a .22LR carbine. While they might be very useful for practice and plinking, I have trouble with the idea of incapacitating my defense weapon; but if all you have available are .22LR rounds the conversion does make sense and I'd be glad to be able to do it. I agree the 5.56 can be very accurate as is true with any high speed, flat shooting round. The .338 Lapua is supersonic at 1.5 miles and is a very flat shooter; difference between the 5.56 and .338 Lapua round is of course bullet weight. A light round like the 5.56 is more heavily influenced by the environment (wind, rain, foliage etc.) than a heavier round. The AR was designed to be used full auto; that was the entire justification for the platform. The M14 was too difficult to control on full auto so the M16 was created. It handled full auto well (a major part of my boot camp rifle training was singing the praises of the M16 on auto. How many films have you seen of troops taking 'single' shots with an M16? Since I don't see full auto in my survival scenario, why would I want a platform that needs to be at full auto to accomplish its mission – especially since that mission (infantry in the attack) is one I do not intend to be engaged in?
Your AK problem may not be the rifle but the ammo. While I've don't own a chronograph, from experience I know that much of the ammo from communist bloc countries burn very irregularly. If the ammo is inconsistent the rifle has no chance to be accurate. You might get some of the domestic (Winchester makes it I think) and see if that helps the shot groups.
this is just one mans veiw, but 5.56… good luck with big game hunting, and if i have something, if your looking for personal defense for human contact, if you cant get the job done with a reliable side arm, dont get into that situation… you can get a mosin nagat 91/30 for less the $200, the ammo is cheap and plenteful and it puts lead on target out to 800 reliable… just sayin…
About the 'necessity' of a piston system, I don't know if URLs post here, but this tech note from Armalite's site makes my point rather better than I can describe here: http://www.armalite.com/images/Tech%20Notes%5CTec…
Basically, the AR mechanism, incorrectly referred to as a 'direct impingement' system, can be more correctly referred to as an 'internal piston' system (why do you think it has 'gas rings', more commonly called 'piston rings'?), whereas the AK series, the M1/M14/M1A types, and the FAL, etc. are 'external piston' systems. When adding an external piston to a rifle designed for internal piston operation you drastically change the force vectors in the rifle. This can lead to premature upper receiver failure for a rifle that sees more than 20,000 rounds – tests by the Army on retrofit piston systems have shown stress cracks develop at the junction between the barrel and receiver. That being said, you may never see 20,000+ rounds or stress cracks, but I don't like modifying Stoner's original design just so I have to clean it less. Stoner was an accredited engineer, some say genius, and looked what happened to our soldiers in Vietnam when McNamara's 'Whiz Kids' tried to modify his design: removing chrome lining, 30 round magazines that were very poorly designed, and switching to dirtier ball powder are but a few things that got more than one man killed. Plus take into consideration the following articles about the 'need' to clean a 'DI/DGI' system: http://vuurwapenblog.com/2010/08/27/cleaning-your… http://www.defensereview.com/the-big-m4-myth-foul…
Makes you think twice about gun shop BS from the salesman steering you to buy that $4000 hunk of plastic from Germany (or even Bushy/Magpul).
Let's remember one thing here; if the theoretical SHTF ever does happen (devil's advocate), we aren't going to be using our rifles in Iraq. We'll be using them here. Whether there is any truth to the AR system not being reliable in a sandy environment is irrelevant because that's not where we live, and it's beyond unlikely that any of us will ever find ourselves and our personal ARs transported to the Middle East.
The Best Survival Carbine (AR Style Rifle), so after reading all the material and reading everyones View I will post mine.Lets keep it simple,the best is what you are familiar with.I have a 22mag bolt that I have owned from the age of 14,Im 58. Ar style is the easyest to learn and break down and build.Common round.can be switched to 22lr,upper to a .308 when needed.Mass prduction of this unit ensures a knowledge and easy fit to most budgets,Del-ton kits from $500.00,need lower(purchase local..$95.00) to a _ AR-10A4 RIFLE 7.62 AramLite..$1600.00..depends on your budget…So again easy to use and easy to learn to take apart and rebuild,Lets keep it Simple..:}New systems of how gas is despered is like talking about the difference in a 20 oz hammer and a 16 oz hammer.Its how you HOLD the Hammer that matters and how you swing it.. have a good Day .Matt
Cman,
I own a couple – one pump and one single shot. In my youth I took my share of fowl and rabbit with a single shot .410. OOO buck is also a very effective round in a .410. For us guys, stateside, the Taurus Judge and Circuit Judge is a long gun and a short gun that will shoot either .410 or .45 Colt. Not bad a at reasonable price.
if we are talking about only having one rifle.. just one to… defend myself and my family in a complete meltdown of western society there is one that is time tested tried and true. AK 47- pros: 1) affordable. 2) reliable. 3) cheap widely available ammo. 4) heavy hitting .30 cal. 4) its a true mud gun( they are very tolerant of neglect). 5) there are tons of them on the planet (parts are a non-issue) 6) it makes an excellent club when ammo runs dry (very durable)… cons: not super accurate ( but accurate enough for DEFENSIVE engagements within 300 yds) as stated above i do not plan on taking on 30 bad guys alone.. or initiating a long range OFFENSIVE engagement… only trying to stay alive in hopes that peace is restored to my region swiftly for the sake of my family. if you are very concerned about the AK 47's limitations in long range accuracy… make trusted friends with an individual that owns a .308/.30-06 bolt action rifle. my $0.02.
A Mini 14 or a Mini 30 will work flawlessly if maintained properly. I would go for the Mini 30 because if you don't go full auto you are hitting harder with a larger round. I have owned an XD in .40 and currently own an XDM 45 in full size configuration. I liked them both and never had a problem but recently picked up a FNP 45 that I like better. The FNP is ambadextrous, has a larger capacity magazine and is hammer fired as opposed to striker fired in the XD. This is just my personal prefrence but check them both out, either way I don't think you will be disappointed
Glock2291 is correct an AR15/ M16/ M4 platform works in all conditions as long as its operator maintains it. Maintenance is the most importan factor though in the reliability of any weapon or other equipment.
I concur re. maintenance. It's like folks who use stainless steel knives because they don't want to take care of carbon steel. My sense is the folks who are able to maintain a tool (rifle, knife, oil lamp) are not going to bat an eye about the occasional carb-cleaner bath in the chamber of a standard M4. I hit 30 years in uniform next month and I would not think of not carrying a little bottle of LSA or baby can of WD40, with ANY weapon. To each his own, but the folks who have been there/done that are probably going to come down on the side of whatever they are most comfortable with. And I like the fact that if we meet some rainy night under a poncho I can swap parts with you. Very cool
Totally agree w/Guest & FTW. You'd have to be constantly engaged bustin caps for days and days before it would effect reliability. Additionally, if you can't clean it, squirt break free all over the bolt & carrier area and dirty or not, she'll still bark.
I think some people might be misunderstanding what is meant by cleaing your rifle. It doesn't mean fire a few hundred rounds, stop and clean it, fire a few hundred more, and so on. I have personally fired over 3000 rounds through my rifle with no lube or cleaning in between. Keeping your rifle clean just means that when it's time to use it, it's pristine. Most major stoppages that I heard about while in country were from people who rarely cleaned their weapon, but just kept dumping lube in, so when it came time to fire, their bolts would lock up within the first magazine.
If I need to engage a target over 300 meters maybe I should just duck and run. Remember we are talking about a SHTF event here in the US and not in Afghanistan. If the 5.56mmx45 is such an anemic round why is it the one we've reached for for the past 45-50 years? 5.56mm ammo and AR rifles are NOT the sad jam prone weapons they once were.
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