I have seen alot of threads where DI or Piston Systems get kind discussed as a side note. I have been looking at Piston Systems because of this. They are pricey, in fact you can buy another sport for the cost of some of them. Would people with experience or have studied the pros and cons please weigh in on this topic. I would like to understand more before I start saving my nickels. Thanks Guys.

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Grover Oathkeeper

I also want a gas piston driven AR system one day. I've been poking around the net and my opinion...

PRO:

• No hot gasses and fouling exhausted into the action.
• Cleaner running BCG & FCG.
• Requires less frequent lubing since the existing lube isn't getting cooked off and/or fouled.
• Depending on system, you can adjust the amount of gas used to drive the system using a valve.

CON:

1. Hot gas is still used to drive the system, the fouling just occurs in a smaller, potentially harder to clean area.
2. The gas-piston system is not standardized. Every manufacturer implements a different system, meaning only one source for parts.
3. Adds weight to the muzzle end of the rifle.

There is no comparison in the two because of the two factors in my mind. I should also say all of my guns are purpose driven and paper punching is not the purpose, paper is just the practice medium for me, call them insurance or just in case guns.

1. GP's are far and away superior in the number of rounds that can be fired between cleanings.
2. GP's will function longer in dirtier, harsher environments than DI's.

Here are the two negatives I considered with GP vs DI.

1. DI's are more accurate, over 300 yds where it really starts to show up.
2. DI parts are usually interchangeable, if you go GP you should have a large parts inventory or 2 rifles IMO. DI's are cheaper in general as well.

I have Sigs and love them, but they are considerably more expensive than DI's. I should also say my next purchase in rifles will be the M&P 3oo whisper.

While I prefer pistons, DI's are certainly battle proven. To me your budget and the rest of your rifle roster should drive your choice. I have distance rifles and several other specialty products to cover the various roles needed. If you are limited in number of rifles, the accuracy difference with a GP may be a deal breaker for you. JMO.

Which leads to a question, what purpose does the rifle fill for you? Self Defense? Paper Punching, Long Range Shooting/Defense etc. ?

StateRightist....You actually caused me to come up with more questions than answers. I have guns that like you serve different purposes but the bottom line with all of them is that they are "just in case" weapons. As far as semi-autos I have 5: my Sport, a Marlin Model 60 (the long barreled old version), a Hi Point 995 carbine and two pistols. I have large caliber "brush" guns that are effective to 200 yards, and bolt actions that are very accurate to 600. In my way of thinking my Sport is my acronym gun. And I want it to be the best acronym gun it can be. (acronym gun i.e. tshtf, teotwawki tcosawki) But if it is necessary to protect my family, my home and my animals it has to be the best it can be. and someday I will have one with a dust cover but I dont see that being an issue. But it the piston system makes it a better more accurate and more dependable then I would save my nickels until I can do that. But right now the AR basically includes everything in your last sentence.

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Grover Oathkeeper

I think piston systems will come down in price eventually. They are still in the early stages of coming into their own. IMHO I don't think there is any industry standards for PS like the DI systems yet. Every manufacturer has their own design. But that is changing.

Here are a couple of thoughts your post bring in my mind:

1. The DI will be a little more accurate because the tolerances are tighter. The GP more dependable.
2. You have the basic AR in the sport.
3. Sounds like you have covered a lot of the niches. A good lever action is hard to beat for an overall/truck gun out to about 200 yds.

So let me really screw this up for you...lol.

Have you thought about a SOCOM? I have one and I absolutely love it. It is one of my primary SD/Field options. 20 rounds of .308 firepower, Garand dependability, easy to clean, maybe the most reliable action in the word, popular/easy to get caliber, versatile.

I've got a Eotech on mine, I can clean out my yard or pop center mass torso shots at 300 yds with it. I can also pull the Eotech off and use my snap on already sighted scope to hit center mass torso's out to 600 with it if needed. The EBR version of the SOCOM is capable of making 1000 yd shots.

I have .223's, but to be honest, am not entirely enamored of the cartridge in a civilian configuration. The .308 is more versatile and in a SOCOM the rifle does not weigh so much carrying it is a burden. Just a thought.....

Here's a link for someone who could do you a top notch EBR, if you want to spend that much. I'm not sure the stock SOCOM isn't rifle enough, but FYI.

Tools : Smith Enterprise, Inc.

This topic seems to keep popping up on every Forum, and the answers are always pretty much the same. I have a S&W M&P Piston that I wouldn't trade for the most expensive DI AR. The weight of the piston rod, end cap and spring is 6 ounces..think I can handle the extra weight. When I finish a heavy day of shooting I simply remove the rod, wipe it off with a Hoppes 9 soaked rag, reinsert the rod, and then wipe off the bottom of the hand guard. No big deal.

Given that most major gun manufacturers are now producing a piston model, and the Military is considering piston weapons as well, I think they will be here to stay.

As in any Internet discussion, most of the criticism of piston guns comes from people who have never even held one, much less shot one.

My gun has been extremely accurate since it came out of the box. This target was shot at 100 yards using a EOTech HWS:





Shot by my grandson...his first time shooting an AR

Great shooting, I used to have an 8mm Egyptian Hakim MBR. It was Egypt's Semi-Auto that they were using during the 6 day war. A copy of a Swedish design that Egypt bought the tooling from Sweden and started building their own. Heck of a rifle out to 800 yards, about 2 yards long and felt like it weighed a ton (about 12 lbs fully loaded). I probably should have kept it but it destroyed brass after shooting it and you had to adjust the gas valve for whatever ammo you were shooting in it. Was the penultimate acronym gun, but I just didnt like it. I keep looking around and locating parts to build my .243 AR10 although it would be easier to build one in .308 and having my Palma Match Rifle in .308 I could just use the same ammo. But for the time I am just enjoying the heck out of my little sport. And finishing paying it off. LOL OH when Surplus 8mm ammo started drying up it became way to expensive to bang paper with,

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Grover Oathkeeper

If you have a gas piston gun and like it, good for you. However, I wouldn't waste my money on a piston upper. The benefits are overrated, IMHO. If you are going to shoot 10,000 rounds between cleanings it might be worth it.

BTW, two more cons to add to the list:

4) not standardized parts
5) more moving parts.

or more than the few hundred rounds you can get out of a DI between cleanings, assuming is doesn't get grit in it and stop working altogether.

I like my piston to each his own, but I'm not real impressed with your tone. Do you not have enough class to express your opinion politely?

I didn't know you alone were entitled to an opinion. I'm also not sure what DI you have that you're having to clean every few hundred rounds. Like I said, if you have a gas piston and like it, then good for you. You are welcome to your preference. But like it not, my opinion is not tied to yours. BTW, your post exudes class.

I could care less whether you agree with me or not, that's not a problem and your right. "Good for you" and rolls eyes and you can't figure out what prompted my response?

All you need to say was your opinion, save the sarcasm and it would have been fine.

The single most important role a piston driven rifle would have are 2 very specific environments: The frozen tundra (Think Siberia, and North Korea) The other place a piston has a clear ability over the DI is full contact water sports. A piston rifle can be fired half in/ half out of water. They can be completely full of water when you fire them and they will clear the water whereas a Di rifle must have the barrel/ gas system vented or the gas tube will burst, rendering the rifle a single shot.
Other than these 2 scenarios, there is no functional benefit to having a piston over a DI system.
Cleaning: Patrol troops head out with 7 magazines. Yep; that's what ya carry. 210 rounds total. 6 in the front pouch, and one in the gun. In any theatre where you are going to re-supply and double to triple this amount of ammo, there will be time to clean the rifle, albeit crudely.
Wear& Tear: The DI system has some common parts wear- extractors and springs are the first and most common part to need replacement. It's the same on a piston rifle. Gas rings will usually need replacing after 10-20,000 rounds, depending on your ability to oil them. (Piston guns wear out piston rings too... they are just on top of the barrel in the piston drive assy. Barrels are good for upwards of 20-30,000 rounds. Unless the mil is making you shoot the new copper bullets they are testing (Don't want the guy you are SHOOTING to DEATH to actually die of lead poisoning....) If so, the copper slugs wear out barrels in 10-15,000 rounds.

Discussions such as these have been around for ever...like when automobiles started coming out with the new "Automatic Transmissions". People said they would never last, you couldn't pull a trailer with one, they would break down more often, etc, etc. How many stick shifts do you see on the roads today??

Time will tell...the military is looking for a new weapon so we'll see which direction they go. By the way, my M&P has no rings...guess you have never taken one apart??

Your M&P piston rifle has no piston ring in its' piston assembly?? I'd think it has to have an internal piston ring, even with an adjustable gas vent up front. Some kind of baffle/ piston assembly in there. Can you tear it apart and take a couple pics for us? That would be cool!

LWRC lost out along with the others on the piston rifle; the gov. took the Colt M4 with some upgrades over the others. It doesn't mean we won't switch up to something different, but not for another 5 years or so. When they do switch, I hope they put more muscle behind whatever pushes bullets downrange. The 5.56 is really marginal at longer distances.(150 yds+)

I won't have time to take any photos until the weekend, but you can use this schematic from Adam Arms. The S&W system is identical to the AA piston. The piston assembly is at the top of the page. The end cap on the right locks into the gas block, the piston rod fits around the gas tube from the gas block, the small return spring, and plastic guide bushing...that's it. Simple design, super easy to clean. And I agree...using a high powered .22 is no way to win a war.

http://adamsarms.net/images/explodedviewdiagram.pdf

The bottom line (for me anyway) is this debate has be raging for a while and there is clearly no clear winner. Both systems have their pluses and minuses. So why should I spend an extra $500 for a piston (rhetorical question)?

Found this video that shows the removal/installation of the piston rod. I paid about 200 more than the M&P15A they had in the gun shop.

Smith & Wesson M&P-15 AR15 M4 with Gas Piston Disassembly & Cleaning.mts - YouTube

Could always start another debate: Semi-autos vs Revolvers; Outboard motors vs Inboards; Plasma vs LED TV's....it's America, we have choices.......

Well this is why we have the S&W board. To discuss the pro and cons of the two. But your right their will always be debate over this topic.