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Other than the Sig being as heavy as a M1A Socom, how does it match up to a COlt M4? How many yards is the Sig 556 good for? What size groups at what range? Does the Sig run as well as an AK with abuse? How does the 10 inch SBR compare to a 10 inch M4. The weak link in an M4 is long term reliability, wearkest in an ak is range, does a sig fill the gap?
 

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Since the Sig556 fires the same round with the same barrel twist I think it would the same range as the M4.

Bore diameter: 5.56mm (.233 inches)
Maximum range :3,600 meters
Maximum effective range:
Area target: 2,624.8 feet (800 meters)
Point target: 1,804.5 feet (550 meters)

I'm sure the SIG556 would out last the Colt M4 firing as fast as it will fire with no jamming or catistrofic failures.

The SIG556 being gas piston operation keeps all the carbon build up out of the chamber area so It makes it not only safer but easier to clean. The Colt M4 all the build up is in the bolt and carrier group gumming up the important action of locking and being able to fire properly.

That's all I'm gonna go with because I might get corrected on some of it hahaha. Hope I helped.

Geardo
 

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I think that when it comes to accuracy, eliminating the weight of the piston operating system on the barrel is a benefit, though when it comes to reliability, avoiding crud build up on the bolt is a benefit.

In summary, I think the SIG will be more reliable, the Colt will be more accurate. Pick your poison.
 

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7art,

Don't you think the more weight would mean less movement during firing? As for follow up shots... or I guess one shot as well. But I could be wrong. Maybe the wieght of movement with the BCG and piston combined is a lot, but that happends after the bullet has left the barrel, right?


For me, follow up shots with the SIG were much more accurate then my GOV issued M16A2 or M4, which are WAY lighter in wiegh. I had trouble with accurate follow up shots at longer ranges. Not with my SIG.

I guess I'm kinda brain storming right now. :idea:

This is a good topic. I will like the way this one turns out.

Ullie, thoughts, facts, experience?
 

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To get the best accuracy, you don't want anything touching the barrel if you can avoid it, that's why match ARs all have floated barrels - so the handguards and sling pressure are not on the barrel.

That's why in (I think I have the right movie) The Band of Brothers, there's a new recruit fixing his bayonet on a Garand, and the sargeant tells him to take it off because the rifle won't shoot worth a darn with it on.

Accuracy is affected by barrel dynamics, where the pressure of the powder causes teh barrel to swell in length and diameter behind the bullet, as the bullet travels down the bore. All of this causes the barrel to vibrate, and adding mass, especially non-symetrical mass, will affect where the tip of the barrel is pointing at the moment the bullet leaves the muzzle.

If you walk up and down the line at the National Matches at Camp Perry, there is a reason why you will not see any of the new piston ARs.

Yes, more weight helps stabilize a rifle during aiming, but in a match rifle, those weights are placed in a shroud that surrounds the barrel, so nothing touches.
 

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SGT_geardo said:
Since the Sig556 fires the same round with the same barrel twist I think it would the same range as the M4.

Bore diameter: 5.56mm (.233 inches)
Maximum range :3,600 meters
Maximum effective range:
Area target: 2,624.8 feet (800 meters)
Point target: 1,804.5 feet (550 meters)

That's all I'm gonna go with because I might get corrected on some of it hahaha. Hope I helped
...hey Gerado

...your figures are for a modern M16 firing M855 ammunition...not a M4...M4A1... :p

...the "published" figures for a M4...M4a1 firing M855 ammunition are...

...Area target ~600 meters

...point target...~500 meters...

...these figures are kinda optimistic though...
 

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alfred10 said:
Other than the Sig being as heavy as a M1A Socom, how does it match up to a COlt M4? How many yards is the Sig 556 good for? What size groups at what range? Does the Sig run as well as an AK with abuse? How does the 10 inch SBR compare to a 10 inch M4. The weak link in an M4 is long term reliability, wearkest in an ak is range, does a sig fill the gap?
...the Sig is the superior design...the Sig will be more reliable...have a longer service life and be easier to maintain and requires less preventive maintence and less often based on round count......

...the "maxium" effective range...whatever that's suppose to mean...of the Sig will be slightly greater due to the longer 16 inch barrel when firing the same ammunition under the same conditions...with the longer and heavier ballistically efficient projectiles...somewhere around 600 meters or so would not be unreasonable...maxium effective range is dependant of muzzle velosity and the projectiles ballistic coefficient...

...with the correct ammunition the Sig 55x / 556 should be capable of shooting close to 1 MOA or so...the M4 / M4A1 will be less accurate...

...a "standard" out of the box 55x / 556 is more accurate than a "standard" out of the box AR...all things being equal...

...you shouldn't abuse any rifle...
 

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7art said:
To get the best accuracy, you don't want anything touching the barrel if you can avoid it, that's why match ARs all have floated barrels - so the handguards and sling pressure are not on the barrel.

That's why in (I think I have the right movie) The Band of Brothers, there's a new recruit fixing his bayonet on a Garand, and the sargeant tells him to take it off because the rifle won't shoot worth a darn with it on.

Accuracy is affected by barrel dynamics, where the pressure of the powder causes teh barrel to swell in length and diameter behind the bullet, as the bullet travels down the bore. All of this causes the barrel to vibrate, and adding mass, especially non-symetrical mass, will affect where the tip of the barrel is pointing at the moment the bullet leaves the muzzle.

If you walk up and down the line at the National Matches at Camp Perry, there is a reason why you will not see any of the new piston ARs.

Yes, more weight helps stabilize a rifle during aiming, but in a match rifle, those weights are placed in a shroud that surrounds the barrel, so nothing touches.

While I love my 556, it's only one in my collection of auto-loading rifles. Your short, but concise and articulate description of free-floating AR barrels is the best I have seen. It's also why my BCM SST 16" 1/8 twist middy is more accurate than my 556 with a wider range of ammo type. It also makes me feel less left out by not having purchased a piston upper yet. :)
 

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SGT_geardo said:
For me, follow up shots with the SIG were much more accurate then my GOV issued M16A2 or M4, which are WAY lighter in wiegh. I had trouble with accurate follow up shots at longer ranges. Not with my SIG.
...the precieved recoil and muzzle rise is considerably less in the Sig 55x / 556 due to the nature of their operating system...this is very clearly demonstrated when firing them side by side...especially in burst fire and full auto strings...the Sig is far easier to control...and has less muzzle rise...

...although weight pays a role in precieved recoil...the Sig 556 is "pretty much" close in weight to a modern M16...which comes in at about 7.5 pounds...without the magazine...ie...M16A2 - M16A4...
 

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Ullie,

What are 'area targets' and 'point targets'.

...the "published" figures for a M4...M4a1 firing M855 ammunition are...

...Area target ~500 meters

...point target...~600 meters...
I think it is self evident, an area target is when you are shooting in the general direction of a group of soldiers or equipment, while a point target is trying to hit an individual ... but if that is true, then the ranges you listed make no sense - area range is less than point range.

Is there a typo, or am I misunderstanding what area and point mean?

Art
 

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7art said:
Is there a typo, or am I misunderstanding what area and point mean?

Art
...yea Art...it's a typo...i edited my reply to correct it...

...one way you can think of a "point target" is that it has a single aiming point...

...an area target "may have" considerable width and depth...and may have more than one aiming point...
 

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Thanks, that makes sense. Though it is still strange that the SIG definition of the difference between area and point targets is 250 meters, while the M-4 difference is only 100 meters. Presumably, their methods of calculating are different. By the time a bullet gets to 500 meters, it sould no longer care what shot it. If it maintains point target accuracy at 500, it does not suddenly turn so the accuracy from one lasts another 250 meters, while the same standard of accuracy is only 100 meters in the other case.

The only explanation for the difference is if bullet velocity and weight were so different that one hit a transonic barrier at 500m, but for similar bullets, twists, and muzzle velicities, this would not seem the case.

Art
 

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SGT_geardo said:
Don't you think the more weight would mean less movement during firing? As for follow up shots... or I guess one shot as well. But I could be wrong. Maybe the wieght of movement with the BCG and piston combined is a lot, but that happends after the bullet has left the barrel, right?
Newton's Second and Third Laws of Motion...basically, when mass is propelled its force correlates directly with the amount of mass. Heavier objects equal more force so more forceful movement. Though, this is mitigated by the fact that you have the same force (the recoil caused directly by the bullet firing) acting on different masses. So, the lighter bolt carrier in an AR type rifle might move faster and with more force since the same recoil might not move the more massive 556 action with as much force. Basically, the more mass an object has the more force it creates when moving at the same speed as a less massive object.

I say might because I do not know exactly how much force is transferred from gas expansion to the actions of each rifle and then what is translated to felt recoil. People who live by the AR that have shot my 556 say it has a much softer recoil. So, going on anecdotal evidence, my guess is that in semi-automatic fire, using the same weight and load bullet, the SIG moves less forcefully (in physics terms not vernacular) since the force that moves it is dampened by its increased weight. I bet though on full-auto the inertia on the SIG would create more difference between the two.

My two cents any physics majors feel free to chime in and critique.
 

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Felt recoil is a function of how quickly a rifle comes back against you.

When the energy of the rearwards moving rifle hits you all at once, it has a larger felt recoil. If that energy can be spread out over some time period, the felt recoil goes down.

A bolt gun hits you all at once, whereas a semi-auto has a spring in it, so the recoil energy has to compress a spring, and it spreads the force out over a few milliseconds.

Obviously, with different buffer springs, the AR vs the SIG will vary slightly how that force is spread out, so I suspect it is spring differences, more than rifle weight that accounts for any difference in felt recoil.

Turn off the gas valve in a SIG, and I expect it will kick a lot worse.

Art
 
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