I got to admit, trying to convert a DGI system to piston is probably folly; but Stoner also designed the AR-18, which he considered superior, and kept the copyright so he could manufacture it. I weighs the same as the AR-16, shoots just as straight - I challenge anyone to tell me the recoil feels any different. I've had pack rats try to put nesting material in the receiver and not affect the ability to operate the action.(purely accidental field experience) The big difference, is I can break it down in seconds, and have the piston squeaky clean in way less time than the old Colt system. It is those seconds that count in combat - not the stupid gas system.

Delta uses a Gas-Piston system (i.e. HK 416) over DI (i.e. M4). Enough said in regards to reliability and accuracy.

Everything has its purpose. DIGS saves weight and allows a more accurate rifle, generally. Pistons 'can' offer better reliability, but they do so at greater recoil Impulse (less accurate) and higher parts count (i.e. higher failure rate eventually). So the solution for the piston rifle is to clean your rifle religiously and to replace the piston parts at the first sign of wear or at specified intervals to prevent.......WAIT A MINUTE, I think I have heard this before! Hhhhmmmn? When a DIGS rifle goes down it is typically (and I only know this anecdotally as I have never had it happen) either dirty and/or dry. YOU ONLY GET WHAT YOU PAY FOR, whether it is $ for a piston system or 'sweat' for keeping your rifle clean and lubricated as you should. In any event a good cleaning or if need be a good hosing out and wet, wet, wet, lubrication will fix it. If a piston rifle goes down...well cleaning isn't usually gonna fix that. It is broken...been there and done that. Short version; was drafted in 72 and retired in 10 and NEVER had, nor have I ever seen an M16/M4 variant service rifle that failed unless broken, INCREDIBLY dirty/dry or had mag problems (all firearms that are magazine fed can suffer from that problem). No weapon system can endure not being cleaned indefinitely (and don't even mention AKs, got really tired of teaching Iraqis and 'Stanis' how to clean their POSs so they would work) and continue to work and give you a high level of confidence. My son was in Ranger Btn (tab and scroll w/ 7 tours) and I happened to be visiting and I asked about 25 of them if they had the chance to pick up an AR or an AK what would they choose. No one mentioned AK. These were all E-4s and above that had CIBs and multiple tours and plenty of 'training' on AKs. They weren't remotely interested. If cleaned and lubricated an AR will not fail you anymore than any other weapon. I always carried the small can of WD-40 and CLP next to my blow out kit when 'out and about'. That is how you keep it running. Be well.

I have been in the army for 11 yrs and never had problem with gas operating systems. I have seen a broken piston before though...take care of ur equipment and it will take care of you...in even in all of the harsh weather conditions...

The most important thing that this article does not mention is how HOT the bolt gets on the impingement system. When you have a round in the chamber, it can cook off. While it is rare, it HAS happened. Also, the heat causes a viscosity breakdown similar to and engine that overheats. The author rightfully mentioned to keep the gun lubed to prevent viscosity breakdown and part wear, but excessive lube creates a whole new problem. Lube collects dust, sand and dirt. While the impingement systems don't necessarily jam from carbon, heat and gas, they DO JAM when they collect too much dust, dirt and sand - like those found in most combat environments (i.e. woods, jungle, desert). This is why most law enforcement don't complain about jams with their impingement guns, because they are not exposes to those environments. Anyway, I hope my comments helped to add value to the discussion.

Joakley....the Sig 556 IS a piston gun.

I wish i could get my hands on an AR15 that shoots like my HK 91! WHATS THE CLOSEST THING OUT THERE? ( I do love piston operated firearms, they seem to be great shooting as well ) ..

Agree to comments when using the Piston system in a Combat environment (Micah) - you get a little extra 'comfort room' for cleaning and fouling. I was in the Gulf, and some other places that challenged my Weapon.....and I was a SAW Gunner....so I too felt it was better and more reliable. I made sure to clean my Weapons (m4, SAW M249). In a Civilian Environment, Hunting, Home Security, or LEO - the Gas Impingement is just fine. Never had one problem if she is kept clean and lubed.

Under extreme combat situations, gas piston rifles have proven themselfs. Look beyond the ak, look at the FN, its legendary.

Re: Joakley The Sig 556 series of rifles and pistols have adjustable piston operating systems base on the Swiss Arms 551 rifle. The 516 and 716 rifles also use an adjustable piston operating system, but maintain the look, feel and function of an AR-style rifle.

The Sig 556 is a DI, its the Sig 516 and 716 that are Pistons

One thing people seem not to realize about military rifle testing trials, is that the makers of m16/m4 rifles pay a lot of money to make sure their designs are used. There are many rifles with better designs than m16/m4s. I carried a m16 in Iraq and was a unit armorer. The M8 was a much better weapon. M249's and M240B are both piston driven. I was a 240B gunner in Iraq. No failures to fire, ever. Granted, if you clean your M16/M4 it will work almost as well, but the piston system gives you a little more leeway in how clean your weapon is. Keep in mind that this was desert fighting. Fine sand in the summer and mud in the winter. Even if you didn't fire your weapon on a mission, it was still dirty when you came back.

Use the powder the gun was designed for and it will run fine.My prob with DI is gas rings,keep plenty of spares or you're out of bussiness.My piston AR uses no gas rings and uses any mill spec bolt.

I guess a gun that can't shoot all calibers is unreliable too?My car has 12/1 compression runs fine on super unld designed for it.

Mikhail Kalashnikov did noting original, he copied Carbine Williams design, he also copied the safety...take a look at a Model 8 Remington and look closely at the safety.

Mike, both Ransom and Panzer SS are correct. The HK91 does not rely on propellant gases in any way. It is unaffected by burn rate, power of the load, or residue. It uses a delayed roller block action.

Mike, The HK91 uses a roller bolt delay NOT a gas system. Not sure what rifle you are looking at but both of mine lack a gas system. BTW, 100% reliable.

Uh, PanzerSS, the HK91 most certainly does have a gas tube and a piston. The piston is attached directly to the bolt through an operating rod which rides in the gas tube that sits on top of the barrel. What, exactly, do you think causes that rifle to function?

Get a HK91 and you don't have worry about either. No gas tube or gas piston there.

A gun that is picky about the type of gunpowder it burns from its cartridges is not reliable... if your car could only run with one particular brand of gas would you call it reliable?

history says this;If the AR had been able to use the ammo it was designed to shoot. Witch it was not.Us had a contract with Olin for powder to power the ammo of the M-14 oh is that a gas impingement rifle? And so to keep out of a law suit US decided to down load the ammo or allow ammo not designed for the AR to be manufactured.So now we have dirty ammo only because US shortcut to keep out of court. Call that strike 1. Then the US knows from experince all about chromed chambers and bore.Ignored to promote speed of build and $$. Stike 2. This is the equivilant of substituting kerosene for high test gas and not making nessasery changes in system to acomodate the change.The M1 rifle & cabine,the M14 and countless other guns all have proven to perform superbly, or nearly as any of the direct blowback systems.

I own a DPMS SASS(AR-10) .308 and a SCAR 17s chambered in .308. No, they're not .223's, but both are great weapons to shoot. BUT, if I had to compare I would take the SCAR hands down. The ease of operation, disassembly, lack of fouling, and low recoil make it an easy choice. Every person, and I mean every single person that have shot both rifles back to back prefer the SCAR. Don't get me wrong, the AR platform is a tried and true platform and I enjoy my AR, but it is outdated and needs improvement to meet the competition head-on. The M-14 was was preferred in Vietnam over the M-16 by all soldiers who could aquire one, and that is definitely not new news. Gas piston AR's do have some advantages over their direct impingement brethren, however, starting ground-up would make the most sense so that the latest advancements can be utilized in the design to help the soldiers in the field and the civilians at the range.

The argument of "keeping it wet" is misleading. The carbon deposits are simply being redirected to some other location in the mechanism to collect over time. You'll still pay the piper and it will likely cost more in time required to truly clean out the system. Avoiding the deposits in the first place is the best way, IMO.

Correct me if I'm wrong but doesn't a DI AR just damage your bolt over time, and bolt assembly's cost a fraction of what your paying in extra $ for a piston AR? If it ain't broke don't fix it IMO

the anti-piston people are just wrong period. some of you talk about respecting your weapon blah blah blah. the military has tested these weapons time and time again and the gas impingement looses everytime! the genrals in charge simply retort "98% is good enough" unbelievable that we send our troopps out with not 2nd or 3rd best but 4th! since Iraq and Afghanistan the military is finally starting to recognize the poor reliability in dirty environments. Many of you are end of the world conspiracy people so if this is what you belive you better get yourself a piston impingement or find yourself loosing to those of us that do have them. by the way, the pisten system is older than the the AR DGI.

The gas entering the bolt carier puts space between the carier and bolt. This force is inline with the barrel and recoil system.The rings on the bolt help seal in the gas, and the two holes in the carier vent these gases to atmosphere.Rings and vent holes all in line with the barrel. This is not the same geometry as the piston systen that exerts its force only to the top of the carier.

The piston system didn't work well in the M1 Garand? In the M-14? Remington 1100 shotgun et al?

AKs do not use a short stroke gas piston they use a long stroke gas piston. The SKS and SVD however uses short stroke systems.

Check out Adcor Bear no carrier tilt and free floated barrel and no hot gas in your eye, all for around $1000 now is there a reason why NOT to get a piston?

If your intention in getting a piston system is so that you won't have to clean it, don't get a gun at all. Respect your gear. I'm also not buying the "WD-40" as an answer to the impingement system dilemma of fouling the action. Hard to swallow the anti-piston argument in light of the AK success and durability. However, just sticking a piston in a gas tube sounds heretical and . . . stupid. It's unfortunate that the AR18 wasn't embraced as it could have been. The SIG is a piston system.

I might be wrong, but i'm pretty sure that the AR18 didn't use a gas impingment system because Armalite had sold the patents over to colt. At the time of the design of the AR18 Stoner had left Armalite and had no involvement in its design. Also Stoner preferred the impingement system over the piston.

Uhhhh..... Nobody wants to mention the AR18... Stoner himself intended to "improve" the AR15 with a gas piston system.

FERFRANS Weapon System. Google it, Yahoo it, YouTube it, search for it.

FERFRANS

for those of us that are still looking at the AR type I would like to know the maker of the "one piston gun that has beaten time after time"

All things evolve in life. Going to the moon was a dream and then became reality and so on in life. It would be a moronic to think that the AR platform can not evolve past a design made how many years ago? Not all piston guns are created equal. I have observed most of the brand name piston guns break (not going to mention names) but there is one piston gun out there that has beaten time after time every other AR made. Do your home work and keep an open mind (Chevy or Ford).... Oh brother here we go again. (if there are miss spelled works sorry, hard to comment from iphone)

I believe my SIG 556 SWAT is not an impingment system. Am I correct?

Gas piston system to many moving parts. In addition a weapon should be maintained and respected not neglected.