DI or Piston?

[MistWolf]

Most Piston-In-Gasblock rifles require that you remove the piston from the gas block now and again for cleaning. They also run without lube on the piston. Between the extra disassembly and the hardened carbon fouling, I find P-I-G (heh!) designs more difficult to clean

[JC5188]

Most Piston-In-Gasblock rifles require that you remove the piston from the gas block now and again for cleaning. They also run without lube on the piston. Between the extra disassembly and the hardened carbon fouling, I find P-I-G (heh!) designs more difficult to clean

I don't like cleaning any of 'em, so I'm with ya.


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[Joe Mamma]

Spartan040, I like piston guns, and particularly the Primary Weapons Systems guns (which are a long stroke design). I've probably stated that and the reasons why many times on this forum.

That being said, you specifically asked in the context of building an AR for yourself. In that situation, I would strongly suggest building a DI gun. There are so many more parts and options available for DI guns. It's a great learning experience for a gun guy. Also, in the event something with your DI build does not go perfectly, it is much easier to diagnose and fix.

Joe Mamma

[mtlung87]

DI for most applications, piston for specialized applications.

[tom12.7]

DI works better for most, there can be some exemptions that can test better for a few with external pistons. The cost is high, the con's are high, and availability for most excludes much of them. If given the same latitude for variations for them, you could have a better DI for this system than an external piston one.

[HeruMew]

This topic, I don't quite understand what it is about this one, but, lets get into the nitty gritty.

I own multiple AR15s. Some get more use than others.

My very first AR15 was an Adams Arms AA15, driven with the carbine length AA Piston. I don't regret that at all, to this day.

Most of us, hell, the Majority of us will not be entering a battlefield with our rifles.

As a commercial consumer aspect, its kinda hard to get any AR that truly won't run less than a few hundred rounds. Is there exemptions to that? Sure. But I think a lot of us can agree that we have a lot of high round counts on one off examples about as often as the one off examples of failure.
(Please don't string me up, I am not implying that PSA will outrun a Colt, but I am confident both would run hundreds of rounds before requiring a cleaning due to stoppages.)

Nonetheless, the gist of the debate here is the benefits vs the weaknesses.

Someone on page 1 mentioned it added a ton of recoil. That has never been my experience. A cheaper entry level AR in DI is almost always over gassed, comes with a carbine weight, and is gunna throw some power with true 5.56 spec ammo. The piston system I have keeps the felt inertia pretty consistent even between different factory ammos, and I have mentioned before, but the piston weight keeps muzzle rise low, and the piston creates very linear recoil vs lifting recoil.

My DI, will now always remain my go to gun, my SHTF, home defense. Not because of any reliability issues, I trust my AA15 too, but parts swapability just doesnt make sense to use proprietary in a potential scavenging/breakage situation.

Ignore the cleaning selling points. Carbon will get in the action still, just not as much. But it's still gun cleaning.

Just make sure you know what you're getting and for what. I bought my AA15 Blem for 525 after discount and coupon, not including FFL. I was 21 buying my first AR and its done that job wonderfully.

Make sure it fits your budget, and importantly, your long term needs.

I still fully support a 6920 as anyones primary and first ar15, I will be stocking up on those for my future kin, as it can't be beaten for true hard starter and training use.

[JC5188]

This topic, I don't quite understand what it is about this one, but, lets get into the nitty gritty.

I own multiple AR15s. Some get more use than others.

My very first AR15 was an Adams Arms AA15, driven with the carbine length AA Piston. I don't regret that at all, to this day.

Most of us, hell, the Majority of us will not be entering a battlefield with our rifles.

As a commercial consumer aspect, its kinda hard to get any AR that truly won't run less than a few hundred rounds. Is there exemptions to that? Sure. But I think a lot of us can agree that we have a lot of high round counts on one off examples about as often as the one off examples of failure.
(Please don't string me up, I am not implying that PSA will outrun a Colt, but I am confident both would run hundreds of rounds before requiring a cleaning due to stoppages.)

Nonetheless, the gist of the debate here is the benefits vs the weaknesses.

Someone on page 1 mentioned it added a ton of recoil. That has never been my experience. A cheaper entry level AR in DI is almost always over gassed, comes with a carbine weight, and is gunna throw some power with true 5.56 spec ammo. The piston system I have keeps the felt inertia pretty consistent even between different factory ammos, and I have mentioned before, but the piston weight keeps muzzle rise low, and the piston creates very linear recoil vs lifting recoil.

My DI, will now always remain my go to gun, my SHTF, home defense. Not because of any reliability issues, I trust my AA15 too, but parts swapability just doesnt make sense to use proprietary in a potential scavenging/breakage situation.

Ignore the cleaning selling points. Carbon will get in the action still, just not as much. But it's still gun cleaning.

Just make sure you know what you're getting and for what. I bought my AA15 Blem for 525 after discount and coupon, not including FFL. I was 21 buying my first AR and its done that job wonderfully.

Make sure it fits your budget, and importantly, your long term needs.

I still fully support a 6920 as anyones primary and first ar15, I will be stocking up on those for my future kin, as it can't be beaten for true hard starter and training use.

Never said it added a "ton" of recoil, but that it was significantly more than a DI...which has practically none, so it is.

What is irrefutable fact...

It is heavier, recoils more, and costs more, than a comparable quality DI gun.

It is my opinion, that there are many "piston" rifles that are good quality and run well, and if that's what a person wants to own, then by all means indulge.




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[HeruMew]

Never said it added a "ton" of recoil, but that it was significantly more than a DI...which has practically none, so it is.

What is irrefutable fact...

It is heavier, recoils more, and costs more, than a comparable quality DI gun.

It is my opinion, that there are many "piston" rifles that are good quality and run well, and if that's what a person wants to own, then by all means indulge.




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Didn't mean to hurt your feelings.

Irrefutable is bit strong for something that can be defined by personal experience and every firearm is different and everyones preferences are different.

That was the point of my post, not to debate a silly point like recoil when so many different factors impact that perception and reality.

[JC5188]

Didn't mean to hurt your feelings.

Irrefutable is bit strong for something that can be defined by personal experience and every firearm is different and everyones preferences are different.

That was the point of my post, not to debate a silly point like recoil when so many different factors impact that perception and reality.

What makes you think you hurt my feelings? Lol.

You don't like irrefutable? Fine. Show me where I'm wrong. I'm willing to learn.


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[Arctic1]

I find it ironic that the most vocal anti "short/long stroke piston AR" member on this board says the following:



Why such strong opinions on something that you have no experience with? You are also incorrect about your assertions (at least in how it applies to the HK family of piston guns). You state:

They also run without lube on the piston.

This is incorrect. See Section 9.2 Lubrication Guide, page 23, in this HK416 Manual:

http://www.geekgunman.com/manuals/416_manual.pdf

Unless shooting suppressed or using a BFA, there is next to no fouling in the upper and lower receiver. As I have stated before, the area with the most fouling on an HK416 is inside the handguard around the gas block.
There is no need to regularly clean the piston or the piston rod (no fouling on this part). The piston itself will be discolored from the hot gases, and if there is any build up of carbon on it, just use a copper brush to remove. Very simple.

The HK is probably 90% parts compatible with a regular DI AR - the parts that needs changing after a while are the gas rings on the piston.

The perceived increased recoil (for the HK) is due to it being slightly over gassed, and as such has a sharper recoil impulse. Shooting the same ammo, the heavier HK will have less recoil (ie rearward momentum) than a similar AR.
The whole "more reciprocating mass" argument is hogwash.

As others have said, if you go piston, choose one that was built from the ground up - don't use a retro-fit kit.
They are pricier
There is less aftermarket support for them in terms of handguards and barrels
There is less flexibility with the gas system