AR-15 + AK-47 = Sig 556?


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Echo9
July 11, 2010, 10:33 PM
I keep reading that the Sig 556 (or the entire 550 series?) is a combination of the AR-15 platform and the AK-47. The main reason given is usually that an AK bolt looks just like a 556 bolt -- and the similarities appear to stop there.

Yes, they're both piston driven, but the AK is long stroke and the Sig is short stroke. And the recoil springs are in different places.

And why is the Sig similar to an AR? Just because it uses a short stroke piston? Because it uses AR mags? Or because they both use a rotating bolt?

Just how meaningful is it that the AK bolt is similar to the Sig bolt? Is something about an AK bolt inherently durable?

Help me out here. How and why is a Sig 556 the lovechild of an AK and an AR?

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nalioth
July 11, 2010, 10:35 PM
You should keep digging.

There are features from lots of precedent firearms in the Sig 556.

As I keep saying, it's a homogenization of all the best features from lots of past firearms, not a "modernized AK-47/AR-15/whatever".

jonnyc
July 11, 2010, 10:46 PM
I thought AR + AK = Galil? Perhaps my math is off.

Echo9
July 11, 2010, 10:58 PM
You forgot to carry the 1. Your welcome.

Quentin
July 12, 2010, 01:39 AM
Where do you keep reading this? I don't see many similarities between the Sig 556 and AK. No doubt newer designs borrow from what's worked before but I think the Sig borrowed from other designs more.

HorseSoldier
July 12, 2010, 02:36 AM
I thought AR + AK = Galil? Perhaps my math is off.

Galil is just an AK with some mods. Has more in common with a FAL after that than an AR.

rd2007
July 12, 2010, 05:09 AM
The 556 is one of the most difficult weapons to find much info on. I am really interested in one, especially now that I've found some places to get some great deals, but it is hard to find very much info from actual users. The specific model I'm looking at is the SWAT Patrol, which I've found for as low as $1200.

Destructo6
July 12, 2010, 11:33 AM
I don't see many similarities between the Sig 556 and AK. No doubt newer designs borrow from what's worked before but I think the Sig borrowed from other designs more.
The SIG 556 is very similar to an AK. Think about an AK with the dust cover welded in place and the carrier coming out the back for tear-down as a result.
Yes, they're both piston driven, but the AK is long stroke and the Sig is short stroke. And the recoil springs are in different places.
No, the SIG is also long stroke. The piston is held to the bolt carrier by the charging handle. To disassemble, you pull the charging handle out, which separates the two, with the carrier coming out the back and the piston coming out the front. The recoil spring is simply wrapped around the gas piston instead of being on a seperate assembly behind the carrier.

The SIG 556 is a very highly refined AK with the control placements and ergonomics (for the most part) of the AR.

DWhitehorne
July 12, 2010, 05:41 PM
Picture of a AK bolt on the left and SIG on the right. I'm bored waiting for the AC repair man so I thought I would snap a picture. Very similar bolts. The location of the charging handle and having the op rod connected to the bolt/carrier is probably the only other similarity between the AK and SIG. David

http://i74.photobucket.com/albums/i260/dwhitehorne/guns/IMG_3471.jpg

Girodin
July 12, 2010, 05:57 PM
I don't see many similarities between the Sig 556 and AK

I was going to ask if he had ever looked at the bolt of each. Thanks for the pictures they make that point clear. The sig may not look much like an AK on the outside but if one is familiar with how each operates it is pretty hard to miss the similarities.

nalioth
July 12, 2010, 06:31 PM
I don't see many similarities between the Sig 556 and AK
I was going to ask if he had ever looked at the bolt of each. Thanks for the pictures they make that point clear. The sig may not look much like an AK on the outside but if one is familiar with how each operates it is pretty hard to miss the similarities.

No doubt the comparison pix could be brought about by fans of many platforms.

The Sig isn't an AK (or an AR15, or a [some other rifle]), it just uses known-good features from it.

Hatterasguy
July 12, 2010, 07:17 PM
No the Sig556 is just a stupid americanized version of the 550. Luckly with two push pins you can turn any 556 into a 550 and remove every hint of anything AR.

The Sig5XX series is a cross between an AK and a Fal, think of them as AK's that went to college.


Personly I think its the best 5.56 carbine made, and its my most reliable firearm. I'm coming up on 3k rounds with zero malfunctions of any kind.

Hatterasguy
July 12, 2010, 07:21 PM
The 556 is one of the most difficult weapons to find much info on. I am really interested in one, especially now that I've found some places to get some great deals, but it is hard to find very much info from actual users. The specific model I'm looking at is the SWAT Patrol, which I've found for as low as $1200.


They are pretty amazing rifles. The only downside is that they are naturaly front end heavy, so its not a rifle you would want to mount a bunch of crap up front on. I wouldn't even put a quad rail up front. Also you have to remember that like an AK the front end gets HOT, so an aluminum rail will transfer the heat and force you to wear gloves if your really putting some rounds down range.

You can get them to balance pretty good with the Swiss forend, and you can screw a bit of rail into that if you want a light. Thats about all I would mount upfront.

I beleive the Patrol version has the shorter piston system with a long barrel, I wouldn't buy this one. The shorter piston system beats itself up a bit more like on the M4's, so unless you are running a short barrel like the 552 its pointless.

http://www.gunbroker.com/Auction/ViewItem.aspx?Item=178861416

I find the closer you get them to the 550 the better they feel, the Swiss have them set up just about perfectly for their military.

Girodin
July 12, 2010, 10:42 PM
No doubt the comparison pix could be brought about by fans of many platforms.

The Sig isn't an AK (or an AR15, or a [some other rifle]), it just uses known-good features from it.

Certainly its not an AK but I believe the point being made was that if one cannot see any similarities they must be looking with their eyes closed.

Echo9
July 12, 2010, 11:53 PM
Picture of a AK bolt on the left and SIG on the right. I'm bored waiting for the AC repair man so I thought I would snap a picture. Very similar bolts. The location of the charging handle and having the op rod connected to the bolt/carrier is probably the only other similarity between the AK and SIG. David

http://i74.photobucket.com/albums/i260/dwhitehorne/guns/IMG_3471.jpg
I read that the bolt also rides on two rails in both the Sig and AK, reducing engagement surfaces and susceptibility to problems from sand, debris, etc -- whereas the AR bolt contacts more of the receiver on the inside, making it less tolerant to fouling.

So that's another similarity I guess.

Hatterasguy
July 13, 2010, 11:46 AM
The carrier is also very similer between the two.

happygeek
July 13, 2010, 04:54 PM
I read that the bolt also rides on two rails in both the Sig and AK, reducing engagement surfaces and susceptibility to problems from sand, debris, etc -- whereas the AR bolt contacts more of the receiver on the inside, making it less tolerant to fouling.


It does, the Sig's bolt rides on rails on either side of the action. I was so used to the M4 at work that when I first got my Sig 556 I oiled down the whole bolt out of habit. I quickly realized that I could just oil the part where it sits on the rails though. The bolt and bolt carrier itself stays very clean, the piston, gas plug, and gas tube get really dirty. The bolt head gets just a little dirty. It weighs noticeably more than a M4, especially on the front end as others mentioned. I don't think of that as being a bad thing necessarily since I'm just shooting mine on the range and not lugging it around on patrol and the weight holds down muzzle climb and noticeably dampens the recoil.

The wife just got me an AK74 :D So when I get back stateside I'll take that thing all apart, look it over, see how it shoots, etc. and then I can compare the two from personal experience and not just what I read on teh interwebs.

One note on the Sig 556 is that if you're a reloader you might not like it. Mine throws the brass really far away, throws it in a large kinda random pattern, and dings most of the brass casings. It does cycle fine with the cheap Wolf stuff though, so I've mostly just been shooting that.

TrickyDick
August 10, 2010, 10:28 PM
I saw a 556 and immediately fell in love... It took the simplicities and reliability of an AK, and combined it with the accuracy of an AR. Its a sharp rifle, I want one so bad, but the wife isn't too keen on me spending that kind of money on a gun. Someday......

wally
August 10, 2010, 11:20 PM
CDNN is running a special where you buy a 556 and get a free 522.

longdayjake
August 10, 2010, 11:23 PM
This thread is fail until it gets some pictures of the actual rifle!

-v-
August 11, 2010, 11:34 AM
From all range reports on the 556 is that SUB-MOA accuracy is achievable with good ammo. I think one member here was able to get .75" 100-yard groups with his using Federal 55gr Match ammo. If you get the M4-style stock, a heavier sliding stock helps to balance the rifle out nicely.

happygeek
August 11, 2010, 12:23 PM
This thread is fail until it gets some pictures of the actual rifle!


http://i183.photobucket.com/albums/x297/fdhs_runner/Firearms/cimg0378.jpg

http://i183.photobucket.com/albums/x297/fdhs_runner/Firearms/P7100222.jpg

So far the AK74 has proven reliable enough to function even with excessive cat hair in the action. I have thus far been successful at keeping them out of the Sig's rifle case and hence can't speak to the Sig556's reliability under similar conditions. Dang cats get into everything :mad:

HexHead
August 11, 2010, 12:45 PM
I'm coming up on 3k rounds with zero malfunctions of any kind.

Is there any finish left on the receiver behind the ejection port?

Hatterasguy
August 11, 2010, 04:28 PM
Yes because I had some sticky velcro on it for the first 2,500 rounds. Than I said srew it some wear looks cool.:D


Now I'm over 3k rounds with zero malfunctions, I still think this is the best 5.56 carbine made.

Hatterasguy
August 11, 2010, 04:30 PM
From all range reports on the 556 is that SUB-MOA accuracy is achievable with good ammo. I think one member here was able to get .75" 100-yard groups with his using Federal 55gr Match ammo. If you get the M4-style stock, a heavier sliding stock helps to balance the rifle out nicely.


Since the barrel is a 1/7 twist the lighter stuff doesn't always do so well. But guys on the Sig forum have posted pictures of solid MOA groups at 100 yards with 70gr+ rounds.

They seem to love the heavy bullets.

stchman
August 11, 2010, 07:07 PM
To me a Sig 556 is a piston driven (superior to DI) AR with a proprietary lower.

happygeek
August 11, 2010, 08:20 PM
I'm not sure why people keep comparing it to the AR like that, other than that they're both 5.56. In the case of the Americanized Sig556 they use the same mags, but so do many other 5.56 rifles; it'd be like saying the ACR or FN 16S are just like piston ARs. The Sig 550 was designed from the ground up with a piston, it wasn't thrown on as an afterthought. I mean, here's a pic from Wikipedia

http://upload.wikimedia.org/wikipedia/commons/thumb/6/6e/Caroline-demontee-p1000529.jpg/800px-Caroline-demontee-p1000529.jpg

and here's a pic of my field stripped Sig556 [was too lazy to take the handguards off]
http://i183.photobucket.com/albums/x297/fdhs_runner/Firearms/p3300283.jpg

As you can see they changed the lower to take AR mags, which I don't see as a bad thing necessarily. But the chamber, bolt, bolt carrier, charging handle, etc. are very different than an AR or a piston AR.

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