They seem to run cooler and cleaner and, i can adjust to the quirks in some of the ammo we get.
Thoughts?
Thoughts?
Sundown Thursday
My thoughts are that if you run a suppressor, anticipate engagements requiring hundreds of rounds to be fired quickly, have limited opportunity to perform maintenance, or just enjoy holding the bolt in your hand after several mag-dumps, then a piston driven AR is for you. If you are just an average AR-15 owner using the rifle for personal defense, competition, hunting, and plinking then perhaps a traditional DI gun is right for you. The DI system guns offer simplicity, lower cost, lighter weight, and often greater accuracy than piston driven rifles. I'm a dinosaur. I bought my AR-15 in 1984 and learned how to take care of it and keep it running. I found it not to be too hard, but then again I could also take down and reassemble my MKII pistol. My DI rifle still works great, so I have never feltthe need to "upgrade" to a piston gun.
Piston AR models are getting fewer and fewer as time goes by. They were the "hot" item a few years ago but more manufactures are getting out of building them.
I don't believe the crap about piston models being more accurate either.
I don't believe the crap about piston models being more accurate either.
The direct impingement [DI] system is clearly a simpler system. It is generally lighter and has slightly fewer moving parts. However, its major flaw is that it introduces hot and dirty gases into the receiver. That being said, that flaw is not really a show stopper.
The piston systems are better suited to long strings of fire when there's no opportunity for maintenance. That is not to say the DI system is unreliable. The DI system works just fine and it is simpler.
If I was in the market for an AR, I would seek out a piston system because I personally think that the one weak link in the AR platform is the DI system. That doesn't mean the DI is terrible, I just prefer the piston systems.
I'm more of a M1A, FAL or H&K 91 kind of guy anyway.
The piston systems are better suited to long strings of fire when there's no opportunity for maintenance. That is not to say the DI system is unreliable. The DI system works just fine and it is simpler.
If I was in the market for an AR, I would seek out a piston system because I personally think that the one weak link in the AR platform is the DI system. That doesn't mean the DI is terrible, I just prefer the piston systems.
I'm more of a M1A, FAL or H&K 91 kind of guy anyway.
For me the bigger upside is ease of cleaning & maintenance with the piston guns. I have two gas piston units, the SR556 & the SR762.
Removing, cleaning and reinstalling that piston setup is easy and quick.
Removing, cleaning and reinstalling that piston setup is easy and quick.
As I see it, the downside to the direct impingement (DI) systems is that they bring the heat and powder residue from the gas port all the way back to the bolt (and your face). The bolt gets hotter and dirtier.
The downside to the piston systems is that they are slightly heavier and have a few more moving parts to break or get out of alignment.
I've shot both types and can't see much difference in accuracy (shooting desert rats at 100-200 yards), but I can't claim to be a crack shot, so better shooters might see a difference. I like the piston system cleanup, but it's not a huge bonus, since there's the piston to clean, as well. I like the idea of the adjustable gas system, but I have to admit I haven't really had to use it, apart from fiddling with it one day at the range.
Jim
The downside to the piston systems is that they are slightly heavier and have a few more moving parts to break or get out of alignment.
I've shot both types and can't see much difference in accuracy (shooting desert rats at 100-200 yards), but I can't claim to be a crack shot, so better shooters might see a difference. I like the piston system cleanup, but it's not a huge bonus, since there's the piston to clean, as well. I like the idea of the adjustable gas system, but I have to admit I haven't really had to use it, apart from fiddling with it one day at the range.
Jim
Nota Bene: I don't own an AR (I'm a Mini-14 guy) and personally don't care for them. I am retired Army, and the M16 was my assigned weapon for several years, so I am familiar with them. Never did like them.
More importantly, my nephew is an Army Infantryman with two tours in AFG and two in Iraq. He knows the M4 quite well and when he bought a personal AR, it was a Sig piston driven one. Time to clean after our collective firings was about as close to a simple cleaning of the Mini-14: meaning very quickly. He marveled at the simplitudiness of cleaning his Sig. I'll accept his judgment on that, but still won't own an AR (I am in love with the Minis and just don't care for the ergonomics of the AR form factor).
But I trust my nephew's judgment, for what its worth. For a few hundred rounds, it probably won't make a difference in shooting; but the cleaning time...the gas piston wins hands down. "Pay me now or pay me later"...
More importantly, my nephew is an Army Infantryman with two tours in AFG and two in Iraq. He knows the M4 quite well and when he bought a personal AR, it was a Sig piston driven one. Time to clean after our collective firings was about as close to a simple cleaning of the Mini-14: meaning very quickly. He marveled at the simplitudiness of cleaning his Sig. I'll accept his judgment on that, but still won't own an AR (I am in love with the Minis and just don't care for the ergonomics of the AR form factor).
But I trust my nephew's judgment, for what its worth. For a few hundred rounds, it probably won't make a difference in shooting; but the cleaning time...the gas piston wins hands down. "Pay me now or pay me later"...
Additional downside to piston systems is that every manufacturer's "patented" system is just lightly different so parts interchangeability is virtually non-existent.
DI systems are pretty standardized so if something breaks, you don't have to hope that the manufacturer who originally designed/built your piston system is still in business.
If there is any accuracy difference, I would guess it might be because the piston system models are higher priced and they have enough margin so they could put a slightly better barrel in the mix.
DI systems are pretty standardized so if something breaks, you don't have to hope that the manufacturer who originally designed/built your piston system is still in business.
If there is any accuracy difference, I would guess it might be because the piston system models are higher priced and they have enough margin so they could put a slightly better barrel in the mix.
Here we go again, piston versus direct impingement. If this horse has not been beat, beat, ran over, drop kicked, taken out by chuck norris, reassembled, and beat again I do not know what has. Its equal to the argument between wheel guns, and semi auto pistols, the beretta m9 and 1911, m14 and m16, ford vs chevy, and many other which one is better disagreements. 
This was a crazy test of a direct impingement gun. 830 rounds, barrel failed, not the bolt, not the gas tube,
https://youtu.be/BSizVpfqFtw
Here is the gas piston ar crazy test, kinda ironic it had the exact same amount of rounds through it that the direct impingement gun ate up when it failed. Would have thought the gas piston gun would have gone way longer.
https://youtu.be/CfZcEjdvx8c
You make your own assumptions, I got a few jabs in on this dead horse as well.
This was a crazy test of a direct impingement gun. 830 rounds, barrel failed, not the bolt, not the gas tube,
https://youtu.be/BSizVpfqFtw
Here is the gas piston ar crazy test, kinda ironic it had the exact same amount of rounds through it that the direct impingement gun ate up when it failed. Would have thought the gas piston gun would have gone way longer.
https://youtu.be/CfZcEjdvx8c
You make your own assumptions, I got a few jabs in on this dead horse as well.
I’ll just add that the basic concept of a gas piston has been around for a long time, the direct impingement idea is much newer and as far as I’m concerned (opinion coming here) is ingenious. Stoner was a bright guy, as was John Garand and as was also “Carbine Williams” and also Kalashnikov. All the different systems have their advantages and disadvantages. Keep in mind the accuracy we are talking about for combat situations is at average combat distances. It IS a pretty dead horse but it’s fun to debate.
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
It is a fun debate!
I've always thought the piston-driven ARs were throw-backs to the M1 Garand and the M14 (and the StG-44, SVT-40, SKS and AK-47) with their pistons mounted right at the gas ports. The AR series (and M-16/M-4 series) are innovative in their use of the bolt itself as the piston.
The big advantage of the whole AR series is the ease of disassembly, which includes, on the piston models, the ease of getting at the piston (compared to the M1 Garand and M-14, not the AK-47/AKM). This is a great plus, as is not having to scrape off all of the carbon baked onto the bolt of the direct-impingement models (although you still have to clean the bolt).
Jim
I've always thought the piston-driven ARs were throw-backs to the M1 Garand and the M14 (and the StG-44, SVT-40, SKS and AK-47) with their pistons mounted right at the gas ports. The AR series (and M-16/M-4 series) are innovative in their use of the bolt itself as the piston.
The big advantage of the whole AR series is the ease of disassembly, which includes, on the piston models, the ease of getting at the piston (compared to the M1 Garand and M-14, not the AK-47/AKM). This is a great plus, as is not having to scrape off all of the carbon baked onto the bolt of the direct-impingement models (although you still have to clean the bolt).
Jim
If there was ever a place to beat dead horses, it is a gun forum
The AR-15 and its variants have been with us for over 50 years and the DI system is certainly the dominate system. Eugene Stoner was a talented engineer and I think his use of the DI system was carefully designed. I also think it was a calculated compromise. When you look at ArmaLite's other designs from the 1950's and early 1960's, you see the extensive use of lightweight, non-ferrous alloys and plastics. They were clearly trying to keep weight to a minimum. The DI system is not only simple but it is lightweight.
Eugene Stoner was no idiot and he clearly could have used a piston type system or some other system. He made a conscience decision to go with the DI system and I suspect it was selected to reduce the number of moving parts and to keep the weight of the rifle down. For the most part, that calculated compromise was a good trade off.
The lack of additional reciprocating mass attached to the barrel does help with the accuracy potential of the rifle. One of the reasons the AK-47 has such abysmal accuracy is that massive piston and op rod stuck on top of the barrel.
The piston systems used on most AR platforms are relatively light and barrels are typically rather stiff to compensate for the disruption of the barrel harmonics encountered with piston systems. So the accuracy problems with a piston system on an AR are not as pronounced.
However, the DI system does come with a price. The introduction of hot & dirty gases into the receiver is the drawback of the DI system.
With proper maintenance the DI system works fine. It is when the rifle is subjected to high volumes of fire with little maintenance that the DI system becomes an issue. Add dirty environments, particularly dry dusty environments and the piston systems start to look really good compared to the DI system.
The AR-15 and its variants have been with us for over 50 years and the DI system is certainly the dominate system. Eugene Stoner was a talented engineer and I think his use of the DI system was carefully designed. I also think it was a calculated compromise. When you look at ArmaLite's other designs from the 1950's and early 1960's, you see the extensive use of lightweight, non-ferrous alloys and plastics. They were clearly trying to keep weight to a minimum. The DI system is not only simple but it is lightweight.
Eugene Stoner was no idiot and he clearly could have used a piston type system or some other system. He made a conscience decision to go with the DI system and I suspect it was selected to reduce the number of moving parts and to keep the weight of the rifle down. For the most part, that calculated compromise was a good trade off.
The lack of additional reciprocating mass attached to the barrel does help with the accuracy potential of the rifle. One of the reasons the AK-47 has such abysmal accuracy is that massive piston and op rod stuck on top of the barrel.
The piston systems used on most AR platforms are relatively light and barrels are typically rather stiff to compensate for the disruption of the barrel harmonics encountered with piston systems. So the accuracy problems with a piston system on an AR are not as pronounced.
However, the DI system does come with a price. The introduction of hot & dirty gases into the receiver is the drawback of the DI system.
With proper maintenance the DI system works fine. It is when the rifle is subjected to high volumes of fire with little maintenance that the DI system becomes an issue. Add dirty environments, particularly dry dusty environments and the piston systems start to look really good compared to the DI system.
Different strokes for different folks. Everybody is untitled to their own opinion, and what they purchase. So here is my thoughts and what I have bought alot of, and built alot of.
I own many direct impingement ar's .223, 5.56, 6.5 grendel, 6.8spc, 25-45 sharps, 243 win, 308 win, 338 federal. I also own a rra blowback operated 9mm.
The reasons I like the direct impingement rifle are as follows.
Parts interchangeably, and a large supply of available parts on the market., also has less moving parts.
True free floating capability as opposed to the gas piston which I see as non free floating due to the operating rod pushing on the piston, and barrel.
Alot more rail options with the direct impingement, far fewer rails compatible with the gas piston setup due to clearnace issues.
Proven design been around since the late 50's on the ar platform, and even earlier on the mas 49, also a direct impingement rifle in 1949.
Lighter compared to its counterpart, less expensive.
An adjustable gas block like the sentry click adjustable allows the dialing of the gas for performance same as the piston setup.
Con is the gas being blow Into the breech, making a dirtier rifle.
I have never had one fail in the many years I have been shooting them, only issues were during break in with new parts, which is typical with any new gun in my opinion.
Ok the gas piston, comparison...
Cleaner bolt carrier versus the di. However a gas piston does not do away with the gas residue, it just moves it from the bolt carrier to the piston assembly on the barrel, whcih still has to be thoroughly cleaned to keep up reliable function.
Hot gas venting on the barrel where your hand is normally placed.
Most piston systems are proprietary and do not interchange with each other, and less parts availability if something breaks prematurely. Also you have to order the parts from the pistons maker further driving up costs.
Some retrofit gas piston systems have proven to be finicky like the ops 416 system from osprey.
More expensive cost if buying a complete rifle, and extra money if retrofitting an existing rifle.
Carrier tilt issue can be an issue due to uneven pressure from the operating rod on the bolt carrier, wearing the buffer tube aka receiver extension and rear of the lower receiver in extreme cases. I have seen this personally and it does exsist.
My conclusion....
I would own a gas piston rifle like the sr762, since it seems all the bugs have been worked out finally. I also like the POF, and HK 416 gas piston rifles and would own one. But since my needs are already met, i have no reason to switch. If I was just beginning I may have a different outcome, but for me, I will stick with the direct impingement, as Eugene Stoner designed it.
Thats just how I see it and my humble opinion.
I own many direct impingement ar's .223, 5.56, 6.5 grendel, 6.8spc, 25-45 sharps, 243 win, 308 win, 338 federal. I also own a rra blowback operated 9mm.
The reasons I like the direct impingement rifle are as follows.
Parts interchangeably, and a large supply of available parts on the market., also has less moving parts.
True free floating capability as opposed to the gas piston which I see as non free floating due to the operating rod pushing on the piston, and barrel.
Alot more rail options with the direct impingement, far fewer rails compatible with the gas piston setup due to clearnace issues.
Proven design been around since the late 50's on the ar platform, and even earlier on the mas 49, also a direct impingement rifle in 1949.
Lighter compared to its counterpart, less expensive.
An adjustable gas block like the sentry click adjustable allows the dialing of the gas for performance same as the piston setup.
Con is the gas being blow Into the breech, making a dirtier rifle.
I have never had one fail in the many years I have been shooting them, only issues were during break in with new parts, which is typical with any new gun in my opinion.
Ok the gas piston, comparison...
Cleaner bolt carrier versus the di. However a gas piston does not do away with the gas residue, it just moves it from the bolt carrier to the piston assembly on the barrel, whcih still has to be thoroughly cleaned to keep up reliable function.
Hot gas venting on the barrel where your hand is normally placed.
Most piston systems are proprietary and do not interchange with each other, and less parts availability if something breaks prematurely. Also you have to order the parts from the pistons maker further driving up costs.
Some retrofit gas piston systems have proven to be finicky like the ops 416 system from osprey.
More expensive cost if buying a complete rifle, and extra money if retrofitting an existing rifle.
Carrier tilt issue can be an issue due to uneven pressure from the operating rod on the bolt carrier, wearing the buffer tube aka receiver extension and rear of the lower receiver in extreme cases. I have seen this personally and it does exsist.
My conclusion....
I would own a gas piston rifle like the sr762, since it seems all the bugs have been worked out finally. I also like the POF, and HK 416 gas piston rifles and would own one. But since my needs are already met, i have no reason to switch. If I was just beginning I may have a different outcome, but for me, I will stick with the direct impingement, as Eugene Stoner designed it.
Thats just how I see it and my humble opinion.
Although you do have to clean the piston, it’s generally less complex (fewer nooks and crannies) than the AR bolt. Getting the carbon out of the inside of the bolt still takes me back to infantry basic and the drill instructors “rejecting”inadequately clean bolts.
Jim
Jim
I love my SR556, it's very, very accurate. And it's just as easy to clean as my AR556.
The only negative of the SR556 to me is the weight. The piston assembly hanging out there makes the front end heavier. But I love the gun, and will never get rid of it.
The only negative of the SR556 to me is the weight. The piston assembly hanging out there makes the front end heavier. But I love the gun, and will never get rid of it.
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