I've changed my opinion on piston driven rifles.

Well, I really haven't added to my Sport. I, however, have replaced two parts on my Sport, an LMT adjustable rear for the MBUS, and M4 handguards with heat shields for the stock handguards. But, it sounds like many people replace those parts anyway so maybe S&W installed the bare minimum because most were stripped off quickly after purchase.

As for the piston system, I understand the benefits but I will probably not install one. My goal is to keep my Sport as light, simple, and inexpensive as possible.

A.O. said:

I've never had a piece of chevy outlast the payments.. GM is not in my future!! YMMV

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You could go import then.

jdh said:

You could go import then.

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I've had 3 Dodge trucks in a row now with no problems...

My '07 Tundra is truly American made by Americans in San Antonio, Texas. Best truck I have ever owned and after 109,000 miles the only thing I needed fixed at the dealer was the Made in China radio. I have owned all of the others at one time or another, and all had major problems after a few years. I'd buy another Tundra in a heartbeat.

My M&P15 Piston has given me the same reliability as my truck, and I will never own another DI gun again.

JaPes said:

I've changed my mind about piston driven rifles in general, and my opinion that AR-15's should all be DI just as Eugene Stoner intended. Why the change? Got back from shooting my Tavor at the range. Cleaning a rifle that doesn't poop where it eats is so much faster and easier.

I'm considering converting my home built AR from DI to piston driven.

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With all due respect...the FACT that the DI version of the M-16 is still around and in ACTIVE service some 50 years AFTER introduction speaks VOLUMES for the "platform."
I personally CARRIED an M-16 into combat in 1978 and it NEVER...NOT ONCE, NOT EVER, NEVER, NEVER, NEVER, failed to chamer, fire, extract, eject, and RE-chamber for me!

I carried that ******* up and down the mountainous rain forests of Panama and it NEVER failed...NEVER! I'm not quite sure exactly what a "gas piston" system can bring to the table to make me think IT is the proverbial "Cat's Meow!"

Today I own a "rack" of AR type rifles, all DI, and ALL have worked 100%

Just saying...for the sake of those who buy the AR-15, "as is" and don't necessarily want to drop $300+ into a piston conversion!

For all those who have shelled out CASH for a "Mil-Spec" operation AR-15....YOU'RE perfectly FINE with the DI system!!!!

A.O. said:

I've never had a piece of chevy outlast the payments.. GM is not in my future!! YMMV

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My 92 3500 had 350K on the odo when the 2011 wildfire got it. I've owned a few Dodges. Even and AMC or two. The closest to a Ford has been a Mazda. I'm not a brand groupie. I buy what interest me.

Oh to get back to the subject of the thread. Piston ARs do not.

JaPes said:

I've changed my mind about piston driven rifles in general, and my opinion that AR-15's should all be DI just as Eugene Stoner intended. Why the change? Got back from shooting my Tavor at the range. Cleaning a rifle that doesn't poop where it eats is so much faster and easier.

I'm considering converting my home built AR from DI to piston driven.

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JaPes, I know this is an old thread but what is your opinion of the Piston Driven rifle compared to the DI rifle.

Any new updates?

Nothing new.

I prefer civilian semi-auto rifles patterned to look like military only rifles that have gas piston systems native to their design. The reason I prefer gas piston systems has not changed: they don't poop where they eat and I find them easier to clean. There is nothing blowing back into the action, the receiver stays clean. Combustion gas carbon fouling is concentrated at piston. Of the two types of gas piston systems, I prefer the simplicity of the long stroke gas piston system (piston, connecting rod, carrier all one unit) to the short stroke gas piston system (piston, connecting rod, carrier separate pieces).

I will say that there is nothing wrong with the DI AR-15. There is no added reciprocating mass of a long stroke gas piston. There is no added complexity and small parts of a short stroke gas piston system. The DI system is stupid simple. Replacement gas tubes are cheap. Replacing gas tubes is easy.

While a piston AR-15 doesn't poop where it eats, there are negatives. The AR-15 is built on standardized parts and dimensions. A gas piston is not native to the AR-15, so gas piston systems are not standard across all AR-15's. Choosing to buy a piston driven AR-15 locks you into a single source of gas system parts and matching carrier key. Building your own gas piston AR-15 or converting an existing one adds to parts selection deliberation and complexity because the system is not native to the AR-15. Which piston system to use? What carrier to use? How does the system cope with carrier tilt? Do I have to purchase a special buffer? IMO, if you want to go the gas piston route on an AR-15, buy a factory complete gas piston AR-15.

Regarding converting my AR-15 to a short stroke gas piston system, I didn't do it. I abandoned the AR-15 platform. A Tavor and AK-M cured me of black rifle disease.

Until the Tavor is as cheap as a used 6920 I'm sticking with the AR.

Dispite having mostly long stroke gas pistons I actually prefer the short stroke. Don't know why, not for any real reasons. The two are practically the same thing.

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Ill take my Scars any day !!

Just my opinion but there is nothing wrong with either system and they both have their advantages and disadvantages. Pick your poison.

The only thing I will say is in agreement from JaPes, buy it from the factory if you go piston. "Upgrade" kits do not work well and if they do work, won't work well for as long as a designed from the ground up rifle.


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see the light...

JaPes said:

I've changed my mind about piston driven rifles in general, and my opinion that AR-15's should all be DI just as Eugene Stoner intended. Why the change? Got back from shooting my Tavor at the range. Cleaning a rifle that doesn't poop where it eats is so much faster and easier.

I'm considering converting my home built AR from DI to piston driven.

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"I once was blind, but now I see."

Stoner also included a chrome chamber in his design, but McNamara decided that "they don't need chrome on their guns." That, added to the jamming caused by DI fouling, helped add to the list of names on the Black Wall over by the Lincoln Memorial Meanwhile, the enemy pressed on with their choice of infantry weapons, along with 60 million others that will run like a battery bunny. Have you seen the video on the tube of the guy who runs an AK until the furniture ignites-and continues...?

I appreciate everyone's opinion.

Sorta kinda Looking at the Ruger SR 556 but I'm not familiar with the two-stage piston.

Has anyone had any experience with the two-stage piston?

Gunsumerreports.com has a review of the rifle but it's dated 2010.

What you have in the SR 556 in a nutshell.

1. Round fires.
2. Combustion gasses travel down barrel.
3. A portion of the gasses is diverted from the barrel to the adjustable gas regulator.
4. The gasses exert force on a small gas piston.
5. That force is transferred to a transfer rod.
6. The transfer rod impacts the key on the top of the bolt
7. The the impact cycles the bolt.

If you want a SR-556 go for it. If anything goes wrong, call Ruger. Their CS is excellent.

Funny that this thread should be resurrected. I was at the small gun store today. Someone made the shop owner an offer he couldn't refuse on his personal AR-15. He needed one ready just in case he wanted to shoot. He assembled one:

• H&K 416 complete upper kit including the H&K buffer and buffer spring.
• LMT Lower
• Geissele Trigger
• Remington Defense free float fore end
• Sopmod Stock
• An LMT rubberized grip. I honestly don't know which one.

He didn't mess with installing an Osprey Defense gas piston conversion or anything of the sort. He chose a complete H&K upper kit with H&K buffer and spring to build a piston driven AR-15. Impressive rifle. If I could build one at dealer parts cost, I still wouldn't. If I ante in that much dough, I'll just save up more and buy a factory complete H&K 416. Once I had that money, I still wouldn't do it. I'd probably buy a SCAR 16 or go .308 with the SCAR 17 Heavy.

I guess my point with gas piston driven AR-15's is that the gas piston system adds cost and weight to the rifle. While there are benefits from a gas piston system in an AR-15, it comes at an increased cost. If you want a reliable gas piston driven AR-15, you need a factory complete AR-15 (or H&K complete upper + buffer & spring kit). I whine and moan about cleaning. Yes, a DI AR-15 poops where it eats. Yes, it can be a chore to clean and get 100% spic and span. Yes a piston system runs cleaner... but you pay a cost for it.

Ruger SR-556 Takedown (the only SR-556 currently listed on the Ruger website) = MSRP $2,199

Ruger AR-556 (traditional DI) = MSRP $799.99

The$1,400 cost difference between the two to have a piston driven AR-15 from Ruger is a punch in the nuts. Will the average guy who wants to shoot an AR-15 on the range need a piston? No. Would the guy who wants to take an AR-15 carbine class or two need a piston? No. The rationale employed for many AR-15 purchases is for self defense during a Red Dawn, poop hits the fan, world without rule of law calamity. Will the increased complexity of a piston driven AR-15 be of use? In my opinion, no. Complexity adds probable failure points. A piston isn't native to the AR-15, so adding a piston is adding complexity.

The individual with money in hand has to weigh all the pro's and cons to decide for themselves.

Arik said:

Until the Tavor is as cheap as a used 6920 I'm sticking with the AR.

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Exactly. I want the newbies to understand I'm no expert. I'm giving my free opinion, so treat it for what it's worth.

By the time I burn another 6,000 rounds through my Tavor and need to replace the barrel, do you think I'm going to be happy about it? No. There is a single source for replacing the barrel, IWI US. Since it's a single source part, I'm have no choice but to pay whatever they want for it. I'll most likely have to send in the firearm for them to install it. This is increased total cost of ownership.

Newbies have to think about this. By the time an AR-15 owner has to replace a barrel, they can buy a good barrel and install it themselves. That is a total cost of ownership cost savings.

These are things to consider when choosing a rifle.

Arik said:

Dispite having mostly long stroke gas pistons I actually prefer the short stroke. Don't know why, not for any real reasons. The two are practically the same thing.

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Bingo. I own a Tavor and a Russian AK-M (made at the Izevesk Mother Plant). My current preferences for a long stroke are due to what I happen to own. I'm sure I'll change my mined whenever I get around to buying a SCAR.

If you have to have piston rather than direct impingement for cleaning purposes, then get something besides a conversion kit for your AR, or any AR built with a conversion kit, such as the now-discontinued S&W.

The bolt and bolt carrier do extensive damage to the receiver over time, and the only rifle that does not experience this is the Colt LE6940P, with its unique articulating link piston system, which allows for the deflection caused when the gas piston strikes the top of an ordinary bolt carrier, which causes it to nose dive as it goes rearward, which eventually creates a non-repairable gouge in the receiver. So, get the 6940P from Colt, or get something besides an AR platform if you have to have a piston, rather than direct impingement.

Poops where it eats? Yeah, I've heard this before. It's not true, but I understand the comparison.

Yes, the bolt carrier gets dirty, but that's just part of gun ownership. I don't find it difficult to clean. If you clean it every 500 rounds or so, it's easy enough and will keep running just fine. At the last class I went to I fired about 650 rounds without cleaning and never had an issue. I don't imagine I'll be shooting more than that at one go.

My ARs are fine as is. I'll stick with the Mini-14 if I want a piston gun.

Rastoff said:

Poops where it eats? Yeah, I've heard this before. It's not true, but I understand the comparison.

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It's absolutely true. Some AR-15 owners don't like to acknowledge the weakness of the system.

Hot dirty combustion gasses are redirected into the action to act against the bolt/carrier to cycle the action. It poops where it eats. My piston driven rifles impart the energy to cycle the action onto a piston. The piston gets dirty sparing the action from hot dirty combustion gasses. It doesn't poop where it eats.

As I've said, the AR-15 is supposed to be DI. Less complexity, less parts, less to go wrong, less to troubleshoot, lower weight. With standard furniture, an A2 Front sight post, and a stock combat trigger an AR-15 that meets the minimum mil-spec as civilians can legally possess will be darn reliable. They can take more punishment than the average civilian owner is willing to put one through.

Sure. I've run 700 rounds through my AR-15. Cleaning is cleaning. I devoted a thread to all the tools I've used to clean one. Break out the CAT M4 tool to scrape the bolt tail, chamber brush, solvents, swab out the upper, blow out the lower, swab out the buffer tube. Why? The AR-15 throws junk back into it's action.

My long stroke gas piston systems are just as simple as a DI AR-15, but they pay a little bit of a weight penalty. What do I get in return? Carbon fouling concentrates to the tip of a piston. Action stays clean and runs cooler. Chambers are inspected, rarely fouled beyond needing a quick swab out.

For me to get this, I pay a penalty in other aspects. It's a give and take.