AR-15 Gas tube vs Piston
I was getting ready to convert my fixed handle AR to a flat top. I bought a upper with bolt and charging handle. I went to one of the RK shows to get a barrel, tube and gas block. I was told not to go that route and to go to a piston drive. What is the difference, can I still use my upper? Can you regulate the gas block like some aftermarket flat ones or do you even need a block with piston? By the way. My new bolt is Boron coated, was it worth the extra expense? Any help appreciated.
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I'll give you my thoughts on this, a short time ago I was going to order a gas piston conversion kit for one of my AR's. I emailed a seller here on GB about a question I had and he never replied. I guess it gave me more time to think about it and after a while I said to myself why.
I don't think there is a 100% reliable weapon gas piston or not. If I was going into combat I might consider it. I don't really see any advantages but there is some extra expense. Your gonna pay at least $250 and for what.
Do you shoot that much were carbon fouling would be that big a problem.
To gum up a regular AR what's it gonna take 300-500 rounds in a short time. Sure you have less carbon fouling and the barrel will be cooler but you still have got to clean the rifle gas piston or gas impingement
either way you gotta clean it. You also have more moving parts with the gas piston. More potential parts to break. You also pay a lot more for a gas piston gun if you go the new route. Well those are some of the points I pondered and I'm sure some others will chime in here. I think before I would buy a conversion kit I would just go out and buy an AR180. They have gas pistons but then again they were designed that way.
You can still use your upper and nearly any barrel. You can use your bolt but you will get a new bolt carrier. The new carrier will have a lug on it that the piston contacts. You will get a different gas block that matches the rod that comes in the kit. Every thing you need will come in the kit including the bolt carrier. You have to watch out for kits that just have a replacement bolt carrier key and your old carrier. You don't want that type of kit. It's not that hard to do any one with some simple knowledge can install the kit.
As far as adjusting the gas flow, it depends on which kit you would buy. Some have a couple of adjustments and some have an adjustment and an off. The off is used when using .22 cal adapter kits.0 -
I agree with everything Armilite has said with the exception of the following in red.
"Sure you have less carbon fouling and the barrel will be cooler but you still have got to clean the rifle gas piston or gas impingement". The "barrels" on gas "tube" guns and gas "piston" guns get equally hot. The reported advantage of the piston system is it keeps the heat and carbon away from the bolt carrier and bolt.
I have been hearing from guys using the piston conversions that accuracy has been degraded slightly using the piston system. I was going to get one but now Iam not so sure I want one. Sure, it makes cleaning easier and when was the last time you got burned by holding the bolt carrier in your hand.
As armilite said, your adding moving parts by going the piston route, and anytime you do that your increasing the potential for something to break.0 -
From an engineering stand point. I don't think there is a piston system on the market with a large enough op rod to not cause issues in the long run.
If I was going to purchase one it would be a LWRC.0 -
I have used a Adams arms piston kit, I didnt notice any negitive effects on accuracy, but I was useing a good barrel and trued extension. It is actually a bit similar to the Leitner Wise piston system, Just not as robust IMHO..
a piston kit does not mean you should puposefully neglect cleaning, but after 2 or 3 mags you can pop out the BCG and clean it without melting your fingers, thats a good thing. Also the gunk build up in and on the bolt, carrier and reciever is alot less... With the kit I had the bolt carrier was a one piece job.. If you retro fit your gun, you should restake the new striker key. Also I have heard of the retro keys shearing, but that anicdotal, but where there is smoke, sometimes there is flames, and usually a lot of hot air.
I do believe a properly designed piston system will increase reliability past that of a DI gun. I think The adams arms kit, with thier new bolt carrier design, is a good piston system, but it lacks the years of use needed to work out all the bugs.
Also the barrel does get hot as any other gun, if not hotter, the front sight base and piston become the heatsink and One weak point might be the fact that when the FSB expands due to heat the access plug might fly out..0 -
quote:Originally posted by shoff14
If I was going to purchase one it would be a LWRC.
good choice, i have 5 of them, and wouldn't trade or sell any of them even to put food in my "tummy", i also have a Leitner-Wise Defense MOD.1, looks like this:
they all come with a quad rail hand guard, this gas piston upper is so different from all the other piston uppers that in my OPINION put them in the muzzle loader class ! just one caveat .., the LWRCI piston system is quite similar to the MOD 1, simply because it was invented and developed by Paul Leitner-Wise, owner of L-W Defense.
there are so many innovations in this new upper i can not begin to name them all, the most outstanding feature is the barrel can be changed in minutes, the quad rail hand guard can be removed without tools in less than 30 seconds. the best part is the Military is testing this new upper and the "Countashot".0 -
USN,
Do you have a link to this rifle? Also, could you clarify which one you mean is a "muzzleloader"?
Very nice looking rifle BTW.
Edit:
It's not the barrel that gets hotter or cooler it's the gas tube on a straight AR. That little tube gets very hot with compressed hot gasses going through it. A piston assembly dissipates the heat from the gas system but not so much the barrel.
Edit II:
Rsnyder55,
EXCELLENT READ!!0 -
You may want to read the tests that were recently done by the military with gas impingement and piston AR's and then read the discussions after.
Here is one link, there are many more:
http://www.defenseindustrydaily.com/the-usas-m4-carbine-controversy-03289/0 -
quote:Originally posted by rsnyder55
You may want to read the tests that were recently done by the military with gas impingement and piston AR's and then read the discussions after.
Here is one link, there are many more:
http://www.defenseindustrydaily.com/the-usas-m4-carbine-controversy-03289/
Sandwarrior thank you. I'm tossed between GI and piston on a build I am doing. TMI!! LOL0 -
I think this has been covered reasonably well, and for an interesting contrary view, see here:
http://www.defensereview.com/ruger-sr-556-gas-pistonop-rod-ar-15-carbine-ruger-enters-the-piston-driven-ar-fray/
quote:3) It's up against the growing skepticism and doubt about the supposed superiority and/or advantages of gas piston/op-rod ARs over traditional direct-gas impingement (DGI) a.k.a. direct-impingement gas (DI Gas) system AR-15 carbines/rifles. with regard to weapon reliability. There are a couple of important points to be made about this. First, as we've already pointed out in a previous article, there are a number of very knowledgable people out there, including, but not limited to, tactical AR-15 builders out there like John Noveske of Noveske Rifleworks, LLC and Nathan Roads of Next Generation Arms (NGA) and professional military Spec-Operators (including U.S. military Special Forces and Special Operations personnel) that actually prefer the traditional DGI setup over the gas piston/op-rod setup. Not only do traditional direct gas guns tend to be more accurate, lighter-weight, softer and smoother shooting, and mechanically simpler than gas piston/op-rod guns, but there is now growing evidence that they may be as or more combat-reliable and/or durable than some gas piston/op-rod guns, provided the DGI guns (like the Colt M4A1 Carbine, for example) are "sprung right", are properly maintained, and have a barrel of at least 12.5 inches (12.5#8243;) in length. A direct-gas AR-15 SBR with a 12.5#8243; barrel can retain and utilize the standard M4/M4A1 Carbine-length gas system, thus optimizing weapon reliability. Piston guns are easier to clean/maintain in the field since they don't get as dirty inside and don't run as hot, thus requiring less lubrication maintenance. However, the "crud" that builds up inside a DI gas (Direct Impingement gas) AR at high round count is not what causes reliability problems. Improper "springing" and lack of proper maintenance (replacing springs and worn-out parts and providing adequate lubrication) are the most common cause of malfunctions in DGI ARs, not the dirt in the action. Maintain them properly, and they will run.
My personal take on this is that while there probably IS an advantage to a gas piston system under certain conditions, probably 98%+ of shooters will never need it.
Yeah, if you are going to be in a situation where you may have to expend hundreds of rounds quickly in a firefight, and its dirty (eg the desert) and you may not be able to clean or maintain your gun regularly, then sure, the piston-driven gun may be better.
But outside of military combat, how many people get into that situation? Even for SWAT guys who may actually use their guns in "anger", they're still probably not going to be shooting that much in anger, under those conditions, or not not be able to maintain their guns.
Ordinary direct gas impingement AR-15s are pretty reliable if not totally neglected, and being Devil's advocate, in survey, the majority of American forces in active combat right now like their M4 guns. Here's the survey, including the stats on the "Pepsi challenge" alluded to above:
http://www.army.mil/-news/2007/12/18/6649-m-4-carbine-has-high-soldier-confidence-despite-test/
One other potential "problem" with piston systems is that right now, there are a ton of different ones on the market, of variable quality, but no standardized one. So with unclear track records of use, its hard to know which ones of these (if any) may fail after time. Along the same lines, with so many variations out there, its unclear which designs will not be supported in say 5-10 years.
Ultimately, there may be a standardized piston-driven AR-15 system, but probably not until the US military adopts one to drive it, and that may not ever happen.0 -
quote:eantownshootah
Advanced Member
USA
8967 Posts
Posted - 01/25/2010 : 5:24:44 PM
I think this has been covered reasonably well, and for an interesting contrary view, see here:
http://www.defensereview.com/ruger-sr-556-gas-pistonop-rod-ar-15-carbine-ruger-enters-the-piston-driven-ar-fray/
quote:
3) It's up against the growing skepticism and doubt about the supposed superiority and/or advantages of gas piston/op-rod ARs over traditional direct-gas impingement (DGI) a.k.a. direct-impingement gas (DI Gas) system AR-15 carbines/rifles. with regard to weapon reliability. There are a couple of important points to be made about this. First, as we've already pointed out in a previous article, there are a number of very knowledgable people out there, including, but not limited to, tactical AR-15 builders out there like John Noveske of Noveske Rifleworks, LLC and Nathan Roads of Next Generation Arms (NGA) and professional military Spec-Operators (including U.S. military Special Forces and Special Operations personnel) that actually prefer the traditional DGI setup over the gas piston/op-rod setup. Not only do traditional direct gas guns tend to be more accurate, lighter-weight, softer and smoother shooting, and mechanically simpler than gas piston/op-rod guns, but there is now growing evidence that they may be as or more combat-reliable and/or durable than some gas piston/op-rod guns, provided the DGI guns (like the Colt M4A1 Carbine, for example) are "sprung right", are properly maintained, and have a barrel of at least 12.5 inches (12.5#8243;) in length. A direct-gas AR-15 SBR with a 12.5#8243; barrel can retain and utilize the standard M4/M4A1 Carbine-length gas system, thus optimizing weapon reliability. Piston guns are easier to clean/maintain in the field since they don't get as dirty inside and don't run as hot, thus requiring less lubrication maintenance. However, the "crud" that builds up inside a DI gas (Direct Impingement gas) AR at high round count is not what causes reliability problems. Improper "springing" and lack of proper maintenance (replacing springs and worn-out parts and providing adequate lubrication) are the most common cause of malfunctions in DGI ARs, not the dirt in the action. Maintain them properly, and they will run.
My personal take on this is that while there probably IS an advantage to a gas piston system under certain conditions, probably 98%+ of shooters will never need it.
Yeah, if you are going to be in a situation where you may have to expend hundreds of rounds quickly in a firefight, and its dirty (eg the desert) and you may not be able to clean or maintain your gun regularly, then sure, the piston-driven gun may be better.
But outside of military combat, how many people get into that situation? Even for SWAT guys who may actually use their guns in "anger", they're still probably not going to be shooting that much in anger, under those conditions, or not not be able to maintain their guns.
Ordinary direct gas impingement AR-15s are pretty reliable if not totally neglected, and being Devil's advocate, in survey, the majority of American forces in active combat right now like their M4 guns. Here's the survey, including the stats on the "Pepsi challenge" alluded to above:
http://www.army.mil/-news/2007/12/18/6649-m-4-carbine-has-high-soldier-confidence-despite-test/
One other potential "problem" with piston systems is that right now, there are a ton of different ones on the market, of variable quality, but no standardized one. So with unclear track records of use, its hard to know which ones of these (if any) may fail after time. Along the same lines, with so many variations out there, its unclear which designs will not be supported in say 5-10 years.
Ultimately, there may be a standardized piston-driven AR-15 system, but probably not until the US military adopts one to drive it, and that may not ever happen.
I could not agree more with Beantownshootah and this was the point I was trying to make. In my earlier post I mentioned about the barrel being cooler. I was wrong on that part and since I was replying to this at 5:00 am this morning and getting ready to go to work I did not get a chance to go back and proof read it. Some times that happens.
As a side note there have been problems with some kits that just replace the carrier key on your own carrier. The force of the piston pushing back on the carrier has a tendency to lift up on the front of the carrier as it moves backwards. This has caused excessive wear on some of the upper receivers in that area. It is highly recommended that if you use one of these kits that you use a kit that has the one piece carrier.0
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