I just don't get the hate people have for things. I have bolt, lever, DI, piston and blowback. Lover them all for what they are! I wished I had a double rifle of any caliber and a Drilling rifle. If anyone has something they don't like they are welcome to send it to me.
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Which is better and why? Direct Impingement Gas or Piston Operated?
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crashlanding
Well-Known Member
Wow, this went from learning something new to pure entertainment
Like almost every post!
It seems there are pro's and con's of each system. Piston systems are more reliable and DI are inherently more accurate. There is place for both. If I was on a gun fight, I would pick up the piston. If I was shooting paper at 300 yds, I would pick up a long barrel DI. If I am hunting my preferred game, I would pick up my bolt gun.
In theory DI may malfunction due to dirt from the redirected expanding gases and the piston type have more parts to break. But in the real world, how many rounds do I have to shoot to accumulate such dirt to cause DI system to malfunction or how many rounds do I have to shoot in order to break one of additional parts in the piston system. I tried not to clean one of my DI AR and lost count after more than 800 round without malfunction. I have both systems in my AR Rifles and did not noticed any difference in reliability or accuracy with them. One of my piston ARs already shoot past 10K rounds and still going strong except for the normal wear mention before. I'm not saying the theory is not true because my DI system became fouled after 800 rounds and I can see signs of wear in my piston AR as the rod beats the carrier and the carrier tend to tilt up the railway. Recoil are very identical but I can a feel a little snap on the piston as the rod battered the carrier but I hardly sense it, very negligible. If you're planning to have suppressor, go with the piston type. Otherwise, save some money and go with DI. Unless you tend to prefer the piston AR. I love both of them and enjoy them. If I will built another one I'll go with the DI system, not because it's better but because it's cheaper and I already have two piston type A.R.'s. Which ever you decide you can't go wrong with it. Enjoy.
Ok, I have been thinking about all the comments, and I have been watching youtubes on this subject. There are probably at least 100 youtubes on this subject alone.....surprising, but it has been beat to death on youtube.
Here are a few of the ones I think are very good and relevant.
1) It is consensus that a lot of extra dirt and soot gets into the action of direct impingement firearms as a result of that design.
It needs to be cleaned on a reasonable schedule, but is still pretty reliable for most folks use.
2) It is consensus the piston operated systems are heavier, maybe not as well balanced out, and have more felt recoil.
3) It is consensus that with more moving parts, the piston guns cost more.
4) There does not seem to be any consensus on one system being more accurate shooting smaller groups consistently than the other though there is a camp which claims the DI is more accurated due to barrel harmonics caused by the mechanical movement of piston parts mounted near and on the barrel of the piston systems.
5) I think it may be consensus that in extreme prolonged fire cases as in 3 or 4 days of continuous combat with no stops, that the
piston systems might be marginally more reliable (ie, less jams and stoppages) due to their ability to go longer without cleaning.
6) There seems to be consensus that the piston systems are easier to tune and operate with a suppressor in terms of tuning the gas
block or regulator.
7) For operation in or intermittently under water, the piston system is a better design.
Now here are some good youtube reviews which have a lot of information in them:
Now, this next video is one which is very interesting to me on DI vs. Gas Piston on Accuracy
The gentleman that made this had a great idea. Using the same rifle he would convert it back and forth from
DI to Gas Piston and look at the group size.
The BIG PROBLEM I have with his experiment design and results is this.......He used an AR with a 14 inch barrel!!
The theory is that barrel harmonics in the piston system cause inaccuracy due to moving parts attached to the barrel setting up
mechanical conflicts and movement that affect the position of the muzzle at the moment of bullet exit. The shorter and fatter the barrel it is very apparent that the impact of these harmonics will be minimized. Varmint Al has proved that with Finited Element Analysis models on his website. I would love to see a duplicate of this experiment performed with a 20-24 inch barrel AR platform.
Anybody here want to make a youtube?
So, I have to question his results because of the 14 inch barrel, but he had the right idea. (Disregard the AD advertisement at front.)
James Yeager has an interesting hypothesis. He says 40 years of technology design and development have made the two technologies converge and really now there is no difference in results.
Lastly, I thought this was a bit of a new approach and insightful in some ways. The last video using thermal heat imaging to track the hot gas signature throughout the rifle system in both DI and Gas Piston systems. Its not only the dirt and soot that goes into the action of the DI system, but the heat or temperature signature too. What is that doing to the ammo in the magazine or
in the chamber? The thought crosses my mind that in a hot rifle under continuous fire, it has to be affecting accuracy in terms of
burn rate, ES and SD, and group size? You can see that even in a bolt action when you don't have enough of a cooling period.
Here where hot gas is routed back to the bolt on a continuous basis, what is it doing? Interesting.....
I'm still looking at rifles out there. Not too many to choose from with a 24 inch barrel on an AR-10 platform.
What do you think of Precision Firearms out of West Virginia? They do offer some options with 24 inch bbl.
Here are a few of the ones I think are very good and relevant.
1) It is consensus that a lot of extra dirt and soot gets into the action of direct impingement firearms as a result of that design.
It needs to be cleaned on a reasonable schedule, but is still pretty reliable for most folks use.
2) It is consensus the piston operated systems are heavier, maybe not as well balanced out, and have more felt recoil.
3) It is consensus that with more moving parts, the piston guns cost more.
4) There does not seem to be any consensus on one system being more accurate shooting smaller groups consistently than the other though there is a camp which claims the DI is more accurated due to barrel harmonics caused by the mechanical movement of piston parts mounted near and on the barrel of the piston systems.
5) I think it may be consensus that in extreme prolonged fire cases as in 3 or 4 days of continuous combat with no stops, that the
piston systems might be marginally more reliable (ie, less jams and stoppages) due to their ability to go longer without cleaning.
6) There seems to be consensus that the piston systems are easier to tune and operate with a suppressor in terms of tuning the gas
block or regulator.
7) For operation in or intermittently under water, the piston system is a better design.
Now here are some good youtube reviews which have a lot of information in them:
Now, this next video is one which is very interesting to me on DI vs. Gas Piston on Accuracy
The gentleman that made this had a great idea. Using the same rifle he would convert it back and forth from
DI to Gas Piston and look at the group size.
The BIG PROBLEM I have with his experiment design and results is this.......He used an AR with a 14 inch barrel!!
The theory is that barrel harmonics in the piston system cause inaccuracy due to moving parts attached to the barrel setting up
mechanical conflicts and movement that affect the position of the muzzle at the moment of bullet exit. The shorter and fatter the barrel it is very apparent that the impact of these harmonics will be minimized. Varmint Al has proved that with Finited Element Analysis models on his website. I would love to see a duplicate of this experiment performed with a 20-24 inch barrel AR platform.
Anybody here want to make a youtube?
So, I have to question his results because of the 14 inch barrel, but he had the right idea. (Disregard the AD advertisement at front.)
James Yeager has an interesting hypothesis. He says 40 years of technology design and development have made the two technologies converge and really now there is no difference in results.
Lastly, I thought this was a bit of a new approach and insightful in some ways. The last video using thermal heat imaging to track the hot gas signature throughout the rifle system in both DI and Gas Piston systems. Its not only the dirt and soot that goes into the action of the DI system, but the heat or temperature signature too. What is that doing to the ammo in the magazine or
in the chamber? The thought crosses my mind that in a hot rifle under continuous fire, it has to be affecting accuracy in terms of
burn rate, ES and SD, and group size? You can see that even in a bolt action when you don't have enough of a cooling period.
Here where hot gas is routed back to the bolt on a continuous basis, what is it doing? Interesting.....
I'm still looking at rifles out there. Not too many to choose from with a 24 inch barrel on an AR-10 platform.
What do you think of Precision Firearms out of West Virginia? They do offer some options with 24 inch bbl.
Yeah, I saw the one he melted, caught fire, he kept shooting....crazy...
Stammster
Well-Known Member
Veteran...I'm not sure what you're planning on using the AR-10 for, but you may want to consider a Browning BAR if you're looking for a lightweight high power semi.
The new MK3's come in flavors like 30-06 and 270 Win. 7.2 lbs, gas operated, very accurate, and 5+1 capacity, and +/- $1200. There is a DBM version available in 308 with a 10rd mag, but it only comes in a short barrel (18") version currently.
I've got a MK2 Safari lightweight with a 20" barrel in 270 Win. It shoots sub 1/2 MOA with handloads. Great deer and hog gun, and I dare say I've considered it even for elk.
Only downside is the gas block is not adjustable and if you want to shoot slower burning powders than 4350 it doesn't cycle great...but I have read it's possible to get the fixed port re-ported.
The new MK3's come in flavors like 30-06 and 270 Win. 7.2 lbs, gas operated, very accurate, and 5+1 capacity, and +/- $1200. There is a DBM version available in 308 with a 10rd mag, but it only comes in a short barrel (18") version currently.
I've got a MK2 Safari lightweight with a 20" barrel in 270 Win. It shoots sub 1/2 MOA with handloads. Great deer and hog gun, and I dare say I've considered it even for elk.
Only downside is the gas block is not adjustable and if you want to shoot slower burning powders than 4350 it doesn't cycle great...but I have read it's possible to get the fixed port re-ported.
