DI vs Short stroke piston in practical use

M

martlin

New member
Hi! I have some understanding in the differences between direct impingement and short stroke gas piston.

DI: dirtier, warmer, cheaper, lighter
Piston: cleaner, cooler, more expensive, heavier, can be better with suppressors.

What I want to know is if someone who have practical experience with both systems can tell if there is a difference when shooting and operating with these systems? If you disregard cleaning etc, and both are running w/o suppressor, will there be a difference in feel and how you operate the gun when shooting 100 rounds on the range?
 
Piston= more moving parts, more failure points, but still good enough.
DI= less parts, said to be dirty, still works good enough.
 
Piston. Simpler, cleaned, the world std before and after the DI AR platform.

Also allows for a shorter and simpler gun usually. Think AR15 folded vs HK folder.

My final comment…. The AK47 is piston….‘nuf said!
 
will there be a difference in feel and how you operate the gun when shooting 100 rounds on the range?
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The rifle is .223 caliber. It hardly recoils. There's not enough difference between a piston and DI to make any difference in felt recoil.

I'd bet if you were blindfolded and shot both a piston and a DI rifle without seeing them first - you wouldn't be able to tell which type of gun you shot. There's not that much difference.

I have owned a DI and have a piston AR. The difference is some of the parts on a piston rifle will be exclusive to the manufacturer. This means you cannot change those parts for after-market parts.

As someone who owns a piston gun, I would advise buying a DI for your first AR. Far more alternatives are available when changing parts and a greater price range of rifles to choose from.
 
What I want to know is if someone who have practical experience with both systems can tell if there is a difference when shooting and operating with these systems?
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I assume you're looking for people with experience with both systems in the AR??

I have experience with both systems in different rifles, DI with the AR, piston with nearly everything else, so can't tell if you if there is a noticeable or practical different in the ARs, only that when shooting a different gun that uses a piston, any difference between the gas systems is overshadowed by the other differences between the AR and other designs of rifles.

The first military DI gas system rifle I can find is the Swedish Ljungmann, (which began production in 42) and the post war derivatives made in Denmark, and later, Egypt.

The DI system is simpler, with fewer parts, so a bit cheaper, and lighter weight but it does send gas all the way back to the action and dumps it there.

This means the gun runs "hotter" and the action gets dirtier from the powder gas. Piston guns vent the gas much further forward, the only gas in the action if from the bore when the fired case is ejected.

In practical terms meaning during shooting, I've never noticed a difference. Afterwards, when cleaning, there certainly is a difference. :D
 
Even though I wrote the opposite, if this is regarding ar15 di vs ar15 piston, I would agree di is a better place to start. The biggest effect is foldability and dirtiness when suppressed. Otherwise di is cheaper, more common, more likely to run, easier to troubleshoot…..again comparing ar to ar.
 
44 AMP said:
I assume you're looking for people with experience with both systems in the AR??

I have experience with both systems in different rifles, DI with the AR, piston with nearly everything else, so can't tell if you if there is a noticeable or practical different in the ARs, only that when shooting a different gun that uses a piston, any difference between the gas systems is overshadowed by the other differences between the AR and other designs of rifles.

The first military DI gas system rifle I can find is the Swedish Ljungmann, (which began production in 42) and the post war derivatives made in Denmark, and later, Egypt.

The DI system is simpler, with fewer parts, so a bit cheaper, and lighter weight but it does send gas all the way back to the action and dumps it there.

This means the gun runs "hotter" and the action gets dirtier from the powder gas. Piston guns vent the gas much further forward, the only gas in the action if from the bore when the fired case is ejected.

In practical terms meaning during shooting, I've never noticed a difference. Afterwards, when cleaning, there certainly is a difference. :D
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When shooting, either way, the crud has to go somewhere. Seems to me that you end up cleaning different parts for longer is all. Sort of a "which parts do you like cleaning more" question.
 
When shooting, either way, the crud has to go somewhere.
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Quite true. And where is goes is either in or out. The DI system dumps gas into the action, and vents out there. Piston systems do not.

Seems to me that you end up cleaning different parts for longer is all. Sort of a "which parts do you like cleaning more" question.
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That's one way to look at it. Another way is that one system cruds up everything in the action, and literally bakes it on and the other keeps that to the gas piston and cylinder out on the barrel.

There's no free lunch, but my personal experience is piston systems are easier to clean.
 
There's no free lunch, but my personal experience is piston systems are easier to clean.
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I generally agree with this. With that said, there are countless documented examples of DI ARs going near 10k rounds and beyond without a "proper" cleaning (little more than a wipe down and quick lube every so often). Piston systems do tend to be easier to clean (thinking m240, Garand, AK, etc)... but not necessarily less maintenance heavy (though not apples to apples, I doubt there is a documented example of a garand going 10k rounds without a proper cleaning).
 
How long a particular gun will run without a "proper" cleaning depends on conditions, the design (and cartridge used) and is a different thing than the effort needed to clean it. (when you finally do)
 
In my experience using both DI and Piston driven AR designs...

DI tends to be lighter, more accurate, dirtier, and in relation to that blowback going into the action, less reliable. That being said, I have carried DI guns into combat and would do so again without hesitation. A minor increase in maintenance blurs and difference to obscurity. There is a lot to be said for simplicity. In the SOCOM M4's I never had or saw a malfunction with service ammunition in combat. Plenty of them with simunitions and other variants of the AR series. My CAR-15 in 1/75th regularly jammed and always lit the entire platoon up at night when it did work. It was a poor example of the type and probably should have been retired years before it was issued to me.

Piston's are heavier, less accurate, cleaner, and more reliable. There is also more mechanically going on which introduces more failure points especially in the long term. That is simply stating a principle of engineering and it was never an issue that I have direct experience to relate.

All of this is discussing very small margins and my experience. A well designed rifle of either gas system can easily outstrip a poor rifle.
 
I feel that the M16/M4/AR15s with DI is one of the easiest actions to clean, so that advantage of AR piston systems has never been a selling point to me.
 
I feel that the M16/M4/AR15s with DI is one of the easiest actions to clean,
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clearly you didn't have the DI's and Sgts inspecting your rifle that I did. :D

I always found scraping the baked on carbon deposits from the back end of the M16 bolt to be more of a chore than cleaning any other weapon I ever owned, or used.

And, I've owned or used quite a few....:rolleyes:
 
Basic was so short, I don’t remember any one verbal assault that came from a DI over any other topic. After basic training, we had access to solvents and pressure washers to get past the armorer’s inspections. Probably have a point about the bolt tail, but I never thought it to be an arduous task by any measure.
 
Piston's are heavier, less accurate, cleaner, and more reliable. There is also more mechanically going on which introduces more failure points especially in the long term.
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I would be interested in the details on 2 points…

How are piston guns less accurate?

How are piston guns more failure prone? I don’t typically think of AK’s as failure prone.
 
Probably have a point about the bolt tail, but I never thought it to be an arduous task by any measure.
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and in basic, you fired how many rounds?? I can no longer recall how many it was for me, but I think it was around 80, certainly no more than 120 including sighting in, AND qualification. Army, '75.

I would fire more than that in a single day with my own personal AR after I got out of the service, and often several hundred rounds went downrange between detailed cleanings. The getting it completely clean everywhere was more of a chore than my M1A, FAL, SVT 40 or even the HK 91, or my Mini 14.

The HK system, also runs "dirty" but due, I think, to the difference in design cleaning it wasn't the chore I felt the AR to be.

I would be interested in the details on 2 points…

How are piston guns less accurate?

How are piston guns more failure prone? I don’t typically think of AK’s as failure prone.
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My experience is, that people who state that the DI system is more accurate and pistons are more failure prone are stating opinions based on engineering principles, NOT the actual performance of all the different guns using either system.

Fewer moving parts makes the gun more accurate, and more reliable IN PRINCIPLE, reality is a bit different and also making blanket statements about entire classes of firearms based on only one aspect of their designs, ignoring all other factors isn't particularly valid, to me.
 
The most advantageous and creactive part in a DI system is the gas tube, the way I see it. It can be formed to connect two points that are out of alignment. That gives a lot of flexibility, similar to electrical cable or hydraulic hose.

As a bet with a friend over reliability, I fired close to 1000 rounds without cleaning my AR. Not in one session but over months. No problem at all. Stopped when he conceded.

-TL

Sent from my SM-N960U using Tapatalk
 
I fired close to 1000 rounds without cleaning my AR. Not in one session but over months. No problem at all.
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As an experiment, I didn't clean my 10/22 for a DECADE. The gun averaged somewhere between a few hundred to a couple thousand rounds a month. The gun never faltered, never choked failed to function or got sluggish, and never changed its accuracy. When I finally gave up and took it down for full cleaning, there was a good 1/4" inch of powder residue all over EVERYTHING inside the rifle, except where the bold moved.

Not DI, not Piston, but a blow back action. The gas system alone does not determine how reliable a gun is.
 
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