SIg 556 vs AR-15

What are the pros & cons of piston vs non piston?????? I assume that my mini 14 is a piston gun-is that correct????
Seems to me that Piston is just one more thing to break. Someone please enlighten me with a well thought our precise comparason of the pro's & cons of each.
Thanks.
Oh and please do it quickly as I am going to be away from the computer later this afternoon

www.sigarms556.com

I own a Sig 556 and enjoy it a lot. I don't own an AR-15 so I can't compare them. I know Gator owns both so hopefully he'll chime in.

Po-ta-to, po-tah-to . . . .

The mini is just a variation of the Garand system utilized by the M1 and M14 - bled off gas pressure impinges on the op-rod/bolt mechanism either through contact with a piston or a chamber machined into the bolt/op rod.

The AK's and the AR-180's use a piston/rod arrangement and bleed the gas off the top of the barrel rather than underneath ala the Garand design.

Some claim the piston guns are more robust; the only real problem I see with the gas tube sytem over a piston system is with the quality of ammo used in the selection of powders that might gum up the works with fowling. But most any powder that does that will also eventually have adverse build up on a piston gun as well, if no where else then in the barrel gas port. Supposedly that is "self cleaning" with good ammo.

The Sigs are cool 'cause . . . well, they're Sigs. But I personally think the AR design has been pretty well wrung out and found to be more than adequate. I guess it depends on if you plan on using them in extended combat conditions. The mud and the blood and the sand and thousands of rounds down the pipe have a way of showing what works and what needs tweaking.

CAJUNLAWYER said:

What are the pros & cons of piston vs non piston?????? I assume that my mini 14 is a piston gun-is that correct????
Seems to me that Piston is just one more thing to break. Someone please enlighten me with a well thought our precise comparason of the pro's & cons of each.
Thanks.
Oh and please do it quickly as I am going to be away from the computer later this afternoon

Click to expand...

There can be huge differences, especially if you go cheap on the AR.

I will compare my experience between Colf 6920's, 6933's, m4a1's and m4a3's and SIG 500 series.

The Sig will be more reliable in a larger array of conditions - mud, dirt, sand, etc. due to the piston system, and less requirement for lubrication on the bolt, as well as less bolt heating under fire. Under a heavy workload, even in semi automatic fire, the AR WILL eventually fail at the bolt unless it is properly made(as with Colts) - the gas impingement system does a good job of heating up the bolt and breaking down, and removing lubrication. Colt's seem to have the better bolts in all the AR types I have used. AR's and M4's must be kept 'wet' as much as possible to run reliably. Sig's are much heavier up front. Some people complain about the weight of AR's!(pansies). So that may be a factor.

In my experience, a Bushmaster, DPMS, and the like are not built as well as M4 Colts and Colt 6920's and 6933's. I would not even compare those sub-par AR's to a Sig as far as quality and strength of parts and materials. They might hold up for target and play. But, in anything as simple as a 2-3 day carbine course, they tend to give up the ghost long before Colts and Sigs do, in my experience. My issued M4a1 was a rattle box, but otherwise indestructible. All other AR's I have owned have failed, as well. I do not even bother with 'affordable' AR's anymore.

I own a 6933 and a SIG classic. And, I gotta admit the 6933 IS light. However, it is not as reliable as the SIG.

NF

The rear pin that holds the upper of my Sig 556 to the lower broke. It's supposed to be captive. Mine is no longer captive. Thus I have an 1800ish dollar rifle that I "fixed" with a piece of Gorilla tape in order to keep this part captive again. Interesting malfunction. The Holosight that some come with is a bit dubious. Some people have had trouble with the mags as well. You also need to buy your bayonet lug separately off Ebay, since for some reason - despite having every other possible evil feature - the Sig 556 doesn't come with the bayonet lug.

Some people have Sigs that will no cowitness very well if at all. The BUIS units that come with the rifles also look rather fragile compared to hose I have for my M4 clones and the Sig needs a special size BUIS so you can't just use an AR unit. On an AR with a carry handle, you can always just use that or else just run with a BUIS as your primary rear sight if you don't want to put on an optic. On a Sig 556, you pretty much have to install some sort of optic. (The ACOG unit that I actually want costs over 3 grand, thus the dubious holosight is still on my Sig...)

Some gas piston guns come with a little doohickey that you can adjust in order to keep the gun working under adverse conditions. Originally, these were also meant to shut off the gas system entirely so that you could use rifle grenades (in the days before LAW rockets, M203s, et al). Playing around with this can keep an otherwise fouled gas piston gun operable.

You don't have to buy a Sig 556 to get a gas piston quasi AR - the new Rugers are gas piston guns, CMMG makes one, and supposedly Colt has one coming out, though I'm not sure what is going on with that. For extra fun Remington now has the .30 AR chambering which basically duplicates the 7.62x39mm. If someone makes a gas piston gun so chambered, then you'd have... well an AK, but an accurate one sort of.

Anyway... The shorthand thing to remember about non gas piston ARs is that they crap where they eat. Whether this will be a problem depends on how you treat it, what you're doing with it and what you expect from it.

The Sig is indeed front heavy. Whether that is a problem depends on how much other junk you're carrying and what you're doing with it. If you just have it laying around the house or aren't wearing armor, it doesn't really matter. But if you're wearing a vest, rifle plates, and carrying a pistol, IFAK, water, and various and sundry other things, you might not want that extra weight or conversely with all that other stuff you might not notice it any more.

I honestly don't remember whether the Sig has a 1:7 or 1:9 rifling twist. Were it not 2 am I'd go find my manual and look it up.

That can influence things a tad bit if you want to fire either very heavy bullets or tracers (the current tracers really need a 1:7 twist). Colt ARs come with a 1:7 these days, many other brands come with a 1:9 compromise twist.

The Colt AR that I have left is a sort of transitional model made for a while in the mid80s. Mostly A2 features and a 1:7 twist barrel, but no fence around the mag release and A1 sights. My other current ARs are a CMMG M4 clone and a CMMG Colt hybrid that is all Colt parts save for a CMMG lower. I also have a complete A2 style RRA lower.

One of these days I'll get around to getting a Colt 6920. Until then CMMG or better will often suffice. I would not a buy an Olympic, Bushmaster or DPMS though. I was not impressed with the DPMS that I used to own. I do quite literally keep bayonets fixed in case I was wrong about CMMG being good enough.

The AR is going to benefit from being more Lego like in terms of what you can do with it. Caliber conversions, parts, various add ons - all plentiful.

Honestly? I wish someone would make the Daewoo Dr200 again with non gimped features and ditching the 1:12 twist barrel for a 1:9 or 1:7 option. I liked my Daewoo, very reliable, took AR mags, and was light. Oh and put a rail on the top for easy mounting of optics.

For all you could possibly want to know about AR's and all possible variations, this is the go-to place:

www.AR15.com

Just be aware that is a very big site with some extremely strong opinions.

cajun, I just picked up my first AR style rifle. The new Ruger SR-556. It is a gas piston design. I shot it side by side with a Rock River AR-15 with the standard impingement system. The gas piston recoils less. It's an obvious difference and easily felt. The gas system stays much cleaner, longer. It's also much, much easier to clean. Several military veterans of Iraq and Afganistan checked out my Ruger and were very impressed with the gas piston system. They have standard AR's themselves and they said that cleaning them is the biggest problem.

The Ruger has a four position gas piston. You can set it to 0 and it won't kick out the brass and you can work the bolt manually (great for saving brass and suppressors). Set it on 1 for handloaded target ammo. Set it on 2 for everyday shooting. If you're in the desert and you've fired 2000 rounds to save your life and the rifle is starting to jam, just set it on 3 to really work the bolt to keep on shooting.



The brand new Ruger has a suggested retail of $1999. Many originally balked at the price. But they're selling online and in reputable shops for $1400 or even less. I found the Ruger comes with just about all the custom touches I wanted. The Troy battle sights ($260 if bought separately) are outstanding. I shot this 30 round group offhand, standing at 25 yards:



The Troy quad rail would cost $250 (and it comes with three $12 covers) and mounted a Steamlight TLR-1 and a vertical grip for me:



The Hogue grip ($25) is very comfortable to my hand. The rifle comes with three 30 round Magpul magazines ($17 each) which function flawlessly and boast not tipping followers.

Converting to a gas piston system from a standard AR-15 would cost (on the cheap side) $450 up to (on the quality side) $800-$1000.

So the Ruger SR-556 is a very good deal from a major manufacturer. 400 rounds through mine so far without a hitch. It even groups at 1 1/2" at 100 yards with a 3-9x40mm scope.

They are all 'parts' guns a la the "Colt" 1911, and naturally they are only as good as the parts they are assembled with. The truth is (though some purists will argue with a fence post to the death) that most of them these days are more than adequate for the 'avaerage' user who will likely never fire 5000 rounds through theirs or use them under extended combat condition is the field.

I've seen less than satisfactory results out of the "cheapo" AR's and I've seen things fail on the top of the line guns. Quality control in anything (being the frequencey of the fit, finish and materials of construction of the respective parts) is the difference in price, mostly. If the parts are billed as "mil spec" then they have the same requirements/standards of manufacture as the more expensive models.

Cajun:

I've had one particular AR-15 for over 20 years. Over that time, I've changed configurations several times so that it is now a 16" barrel model. When I went to the 16", I bought a new barrell and installed it. It worked fine for about 1000 rounds. After that, it started "doubling" and "tripling" full-auto, followed by a misfead jam. I tried everything I could think of to fix it, including heavier buffers, new gas tubes, etc. When all else failed, I decided to check the barrel gas port. I really didn't believe that could be the problem because the barrel was too new for much erosion to have occured. I found the port to be too large, having apparently been peened down due to an larger than required hole being originally drilled in it. The peening was thin enough that it had eroded.

I didn't really want to get a new barrel at that point, and decided to investigate the piston systems. I found one from ARES Defense (the one now offered by Bushmaster) and ordered it. After the 30 minute installation, I took the carbine to the range with 500 rounds. I began firing the rounds as fast as I could reload the 5 magazines I brought with me. There were no jams or failures of any kind. What amazed me the most, however, was when I removed the bolt to check for carbon fouling and unburnt powder in the chamber, the bolt was barely warm. It could be held in an ungloved hand. In fact, it was down-right cool. Just imagine the amount of interior wear you can save by reducing the heat to that level. Further, there was no fouling, no carbon, no nothing in the chamber or on the bolt carrier or bolt. Accuracy was unchanged, and function was improved greatly. If I could get the budgetary money (no way this year in Kalifornia), I would convert all of my Department's semi and full-auto M4 carbines to the piston system.

Since nobody's mentioned another "racy" gas-piston rifle that's worth a look, I will --- Take a look at the MSAR STG 556, an American made refinement of the venerable Steyr AUG. Ray gun styling, short and handy, "ambidextrous", a choice of colors, lots of fun!

Does anyone have any experience with the Patriot Ordinance AR platform? They are gas piston operated. I have handled one and was impressed with the smoothness of the chrome bolt and receiver. The price is high. I'm not sure I want to put that much money in an AR.