Sig 556 vs AR15

[fwestrom]

I've heard a lot of opinion here about which has better reliability and why, but I haven't heard any backed by facts. Let's see what we can come up with. There have been some credible studies comparing the "reliability" of different weapons in this category..

Dust Test by Army Test and Evaluation Command (1 or 2)

• XM8: 127 stoppages
• MK16 SCAR Light: 226 stoppages
• 416: 233 stoppages
• M4: 882 stoppages

As a side note, my SIG556 BCG is simpler than those of my ARs, and there total number of moving parts is the same or less.
The SIG556 has a long stroke piston system: it uses a piston fixed to the bolt carrier, and they move as one.
That is in contrast with a short-stroke piston system (in most piston ARs) where the piston moves separately from the bolt carrier and only briefly makes contact - a design under which there are more moving parts.

[mikenac]

I think short and long stroke pistons are about equally reliable in reality. The SKS/HK416/XM8 use a a shot stroke piston, while the AK/Sig use a long stroke piston. I am guessing what matters the most is that these guns (piston AR's) were not designed from the ground up to use such a system, thus it's anyones guess how this will affect the operation and reliability. BTW, it's been my experience that short stroke piston rifles are a little cleaner than long stroke piston rifles.

I have used plenty of dirty M-16's in my life. They don't like being dry or full of grit. If you keep them wet (with oil of course) and non-gritty, they will run just fine, even when they are plenty dirty. Grit is the enemy, and the recent tests have all been airborne grit based tests. The looser the fit, and the more mass moving backward, the more reliable the weapon will be in high grit environments. The AR has has a tight fit, and a relatively light mass moving backward on recoil.

If you want to talk about simplicity, the G3 uses a roller delayed blowback system, which really has few parts at all, but gets plenty dirty in comparison to a piston design.

[fwestrom]

I think short and long stroke pistons are about equally reliable in reality. The SKS/HK416/XM8 use a a shot stroke piston, while the AK/Sig use a long stroke piston. I am guessing what matters the most is that these guns (piston AR's) were not designed from the ground up to use such a system, thus it's anyones guess how this will affect the operation and reliability. BTW, it's been my experience that short stroke piston rifles are a little cleaner than long stroke piston rifles.

I wasn't trying to suggest that the long stroke was any better than a short stroke, but merely to note that the particular system in the SIG556 is a long stroke system with fairly few separate moving parts.

I have seen what you mention about the long stroke being dirtier, but more so in other rifles. The SIG556 doesn't have much of a problem with that; after 1000 rounds, I can wipe my finger inside the receiver and it comes out mostly clean.

The short stroke piston designs for the AR platform seem to have the relative advantage of not being placed in a full-length tube, and are therefore not likely to ever release gasses into the receiver (perhaps a design side effect of trying to fit the piston under the AR handguard).

I can definitely second the notion that short stroke vs. long stroke is not likely to make a dependability difference in real terms.

[billt]

Like many I read a lot about the Sig 556, and early on was very impressed with it. I even considered purchasing one. For some reason it either wasn't mentioned in the articles I read, or I missed the fact a large portion of the receiver is plastic. That turned me off as soon as I handled one. I'm sure they run fine, and they do exhibit a good amount of quality, it's just the fact all that plastic really was a turn off. When examined it up close it reminded me of an air soft gun. I'm "old school" and have a hard enough time accepting all that Aluminum on an AR-15. I just bought another M-1A the other day, (a SOCOM 16), and seeing all of that steel was a real plus. But in the end the Sig 556 will sell well, and it has a big following. In todays marketplace that is a definite recipe for success. Bill T.

[fwestrom]

Like many I read a lot about the Sig 556, and early on was very impressed with it. I even considered purchasing one. For some reason it either wasn't mentioned in the articles I read, or I missed the fact a large portion of the receiver is plastic. That turned me off as soon as I handled one. I'm sure they run fine, and they do exhibit a good amount of quality, it's just the fact all that plastic really was a turn off. When examined it up close it reminded me of an air soft gun. I'm "old school" and have a hard enough time accepting all that Aluminum on an AR-15. I just bought another M-1A the other day, (a SOCOM 16), and seeing all of that steel was a real plus. But in the end the Sig 556 will sell well, and it has a big following. In todays marketplace that is a definite recipe for success. Bill T.

I'm at the office right now, so I can't look and see for sure, but I can't seem to picture what plastic you're talking about...

There is a little plastic on the charging handle to make it more comfortable, and a plastic pistol grip, but what else is plastic?

[mythaeus]

I'm at the office right now, so I can't look and see for sure, but I can't seem to picture what plastic you're talking about...

There is a little plastic on the charging handle to make it more comfortable, and a plastic pistol grip, but what else is plastic?

I thought Bill was talking about the handguard at first until you posted this. I can't think of which part of the actual receiver is plastic. I'm in the office too so can't check. I'd think this would be a HUGE deal, especially in reviews and publications, if it were true.

Al

[Pvandunk]

I own a 556 Swat and there is no plastic in the Receiver, The Rubber coating on the Charging handle and the Rubber coating around the outer Charging Channel. Im not getting in this at all lol. I like my 556 the trigger the Recoil and the operation but thats me. I have about 8k Rounds out the Front and only a hand full of of Mag Problems to see what it liked. Like i said thats just me who knows about any one else.. I think they are beastly and front heavy but i like that makes me stronger haha


LOL a airsoft gun Ummmm No unless it was. The 556 is a tank shoot one i dare you you will want one and dont just fire at a freekin peice of paper move around fire mult shots from diff positions there Verry Acc

[d90king]

Doesn't look like to much plastic to me. Without going to the safe and digging it out, I don't remember there being a lot of plastic in the receiver...

[Pvandunk]

^^^ OMFG MY HERO I KNEW I liked you"""NO HOMO""" That IS ROCKIN MAN SBR BEAST I MUST DO IT AS WELL NOW>>>>>

[1911shooter]

The 556 is one of the most accurate rifles we own yes Pvandunk we got out and shot it the other day for a little, glad you handed it to SIG-GIRL, she likes the way it feels she also likes the balence with it being muzzle heavy. I also like the fact i dont hear the spring going Twing in my ear when i shoot it, and the side fold stock is a huge plus. for me
Scott