Sig 556 vs. Colt 6920 (m4)

S

Servo77

New member
OK, I have narrowed down my choices to a Colt 6920 or a sig 556. I will buy one of these two rifles. I have handled the sig in the store. I have never got to mess with an actual colt, but I have had other ar-15 carbines to mess with so I get the basics.

ANyway, I am looking for a little input to help narrow down my decision....which would you want and why?
Also, would the 1 in 7" twist on these two rifles have a negative effect on using XM193 (55 grain), which is what I will primarily be shooting.
 
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+1 for Sig. The weight is made up for with incredible accuracy and a piston system. It will have a very long life span... you will be glad you went Sig.
 
I have both the 6920 and a 556 pistol. Both are well made firearms and have been extremely reliable.

The 556 tends to run cleaner due to the piston design, but is a little more complicated to field strip and requires two screwdrivers to do so. The 556 pistol and 6920 weight about the same, the 556 rifle is 1.5-2# heavier, although if you put a rail on the 6920 you will eat up some of the difference.

The 556 pistol is very accurate despite the short barrel, so I'd imagine the 556 rifle would shoot very well.

I don't think you could go wrong with either.
 
Either one will run fine if you maintain it. Spare parts are more easily available for the Colt.

The 1:7 twist will handle 55 grain loads OK. You may get somewhat better accuracy with heavier bullets but the rifle should still be accurate with 55 grainers. My Colt 6520 with a 1:7 barrel shoots 55 grain ball will easily hold the 10 ring of an SR-1 target at 100 yards.
 
If you don't have any familiarity with the M4/M16 manual of arms, and therefore nothing to unlearn for running the 556, I'd say it's pretty much a toss up and comes down to whichever one you like more. (Even if you do, there's not a whole lot that has to be done different, mostly just the charging handle.)

There's more aftermarket stuff out there for modifying an AR than a Sig, if that matters, though there's enough these days that you can make a Sig as tactical or tacticool as you want. Again, pretty much a toss up.

As for 1-7 twist and 55 grain ammo -- non-issue, in my experience, and the faster rate of twist will let you use better 75 and 77 grain loads if you've ever got a need or desire for longer range shooting or serious defensive carbine kind of work.
 
You only need two pennies to take the Sig apart and it is way easier to clean if you know what you are doing. It has far fewer parts and the ones it does have are very strong and well designed. The ONLY thing I do not like about the non SWAT Sig 556 is the heavy,"fish gill" hand guards but you can easily buy the lighter, far superior Swiss 551 hand guards on www.gunbroker.com or on any Sigforum.com type site. It really is a MUST have change.
The Sig will run OK with the 55 grain bullet but its 1:7 twist is extremely accurate with the heavier bullets from 62 grn and up. If you want stopping power you should be using the 75 jhp anyway not the 55 grn.
Simply put the Sig has the reliability of the AK47 and the accuracy of the AR15. It is the best of both worlds.
 
You only need two pennies to take the Sig apart
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I have seen where you can buy a special pin that replaces the front pin and is spring loaded, so you don't need to use a screwdriver or penny....any thoughts on that?

Also, What options do I have for an iron sight for rear mount with the sig? The flip-up rear deal is not real substantial.
 
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I have the "special" pin on my 556 Commando. It's actually the takedown pin for the 551, but it fits the 556. Some companies like MFI are making aftermarket copies of it, but you can find the factory version if you google it.

As for the 556 vs 6920, I'd have both and prefer my 6920 for matches just because I am more familiar with it. But, I must say that the trigger on my 556 is far superior to my Colt.
 
One of my gun buddies has a SIG and so I get to shoot it. I like it and I would like to own one myself. However, I like to have one or two of everything.

At some point, a slightly superior design loses out if the other design is just "everywhere." I think that's the way it is in the US with the AR. Even Remington and S&W are making AR-15's now. Brownell's puts out a separate catalog with _just_ AR parts in it! (I've spent a lot of time going over it page by page.) As somebody already mentioned, the scales tilt even more toward the AR design if you have US military experience and trained with the M16.

The AR design is mature. Decades of maturing. Parts are everywhere and in a bewildering variety of types and manufacturers. And the whole upper/lower feature of the AR makes it super flexible. Since ATF says the lower is "the gun," you can buy or build as many other uppers as you want without an FFL getting involved. You can have a dedicated .22 LR upper. A 9mm/.357 SIG/10mm upper. 16" M4 style upper. A2 style upper. 24" varmint upper. 18" 6.8 SPC upper. 20" 6.5 Grendel upper. .458 SOCOM upper. On and on and on. Each with their own dedicated sighting system all zeroed for that specific upper. The AR-15 is the T/C Contender of the black rifle world! And with all the aftermarket parts, it is the Glock of the black rifle world as well!

Gregg
 
The AR design is mature. Decades of maturing. Parts are everywhere and in a bewildering variety of types and manufacturers. And the whole upper/lower feature of the AR makes it super flexible. Since ATF says the lower is "the gun," you can buy or build as many other uppers as you want without an FFL getting involved. You can have a dedicated .22 LR upper. A 9mm/.357 SIG/10mm upper. 16" M4 style upper. A2 style upper. 24" varmint upper. 18" 6.8 SPC upper. 20" 6.5 Grendel upper. .458 SOCOM upper. On and on and on. Each with their own dedicated sighting system all zeroed for that specific upper. The AR-15 is the T/C Contender of the black rifle world! And with all the aftermarket parts, it is the Glock of the black rifle world as well!
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One question...I thought Colt used a different diameter of pins so that you could only use Colt uppers and lowers...is this correct or am I confusing with soemthing else.
 
Colt used to use different sized pins for upper/lower assembly, but do not any longer. The only real difference you may notice is if you wanted to exchange the trigger. Colt uses a larger trigger pin, but many aftermarket triggers offer the larger pin size.
 
The following is a range report on the Sig556 Vs the Colt 6920 that I posted last November. I have recently had an issue with the firing pin on the 6920 though this week has been a nightmare and I haven't had the chance to trouble shoot the problem. When I get the chance I'll do so and post the results here. Here is the range report as it was posted:

I have been trying to get to the range to fire my new Colt 6920 for weeks now and today I just decided to put everything else aside and just do it. I took along my SIG556 (formerly SWAT version) with the new 551 style hand guards to see how it handles. Seeing how I had them both on the range I took the opportunity to do a SIG556 versus Colt 6920 range report.

From the moment I picked up my Colt 6920 it just felt right. It is very light and the ergonomics are superb. Magazine changes are a breeze with this carbine as the mag release button is in exactly the right position. All of my magazines (I still don’t have the Pmags that I ordered so I’ll have to test those when I get them) feed reliably and release cleanly. I did have an issue with a SIG polymer mag not locking back the bolt when the mag was empty. I don’t yet know if that is a problem with that particular magazine, those magazines in general, or if it was a one-time fluke. I only fired 120 rounds through the Colt so I only used three magazines, which reminds me, I haven’t used the Colt 20 round mags that came with the carbine yet so I’ll have to test those when I test the Pmags.

As I’ve mentioned I only put 120 rounds downrange today with the Colt. It fed the Prvi Partzan M193 55gr with no problems whatsoever. I also only shot at 50 and 25 yards and only off hand. At my range it takes forever for the line to go cold and once again I forgot to take my spotting scope with me. At 50 yards I could use the ACOG on my SIG556 to check out my target so that was the maximum range I shot at today. I started out at 25 yards and then brought it out to 50 yards. At 25 yards off hand I shot 30 rounds with target acquisition being the focus and 30 double taps into about a 4 inch group with some (ten or so) out of the group by various distances. At 50 yards I shot all 60 rounds one at a time fairly slowly and deliberately. I had about a 12 inch group again with some (10-12 or so) being out of the group but all within the silhouette. Now I know that the AR platform is supposed to be more accurate than that, and I’m sure that this one is as well. I would say that even my AK-101 is more accurate than I am. I never have been nor will I ever be a target shooting champion.

Instantly upon firing the first round I had the feeling of déjà vu from my days in the military and firing the M16. I also had the thought that while it certainly didn’t have harsh recoil, it was definitely more than the SIG556. Even so, due to the ergonomics, it was quick to get back on target and it felt like an extension of me. This carbine is a definite keeper.

So, the next thing was to try out the SIG556 with its new hand guards installed. I once again shot 120 rounds and I did so the same exact way as I did the Colt 6920. The 551 style hand guards made a pretty substantial difference in how this carbine handles. The SWAT model’s quad rail was cool and all, but it was very uncomfortable and as most agree it made the weapon heavier and particularly muzzle heavy. As I’ve noted before the ergonomics of the SIG556 are a bit clunky for me. The lower receiver is so long that the controls are simply too far forward. Perhaps if I had really long fingers it wouldn’t be a problem but I don’t so it is. I have worked around that fact by developing a hold which allows me to support the gun with my left hand forward of the trigger guard while the stock is tucked between my elbow and my side. This allows me to move my index finger forward far enough to engage the mag release button and it also frees my left hand to tend to the magazine. I have done this enough that it works, but not near enough to be confident in a combat situation.

Moving on from ergonomics to actual performance. As many others have known for a while, the SIG556 is very reliable and it was no different this time. It fed the Prvi Partzan M193 55gr with no problems whatsoever. As soon as I fired the first round from the SIG556 in its new (to me) configuration I instantly knew that the 551 hand guards are keepers. First off, as I mentioned earlier, the SIG556 has noticeably less recoil and is on the same target MUCH sooner than the Colt 6920. It points really well, but the weight just makes it more difficult for me to be steady on target and it also inhibits swinging and stopping on target smoothly. My groups were significantly tighter... but then again I wasn't shooting with iron sights.

So… my bottom line? If I had to carry the carbine for an extended period of time and/or there were a real chance that I would be in a firefight I would have to choose the Colt 6920. I’m guessing that my familiarity with the AR platform (even though it was a decade and a half ago) just make me much more proficient with the Colt. Conversely, if I had to take off into the woods in some sort of SHTF scenario I would choose the SIG556 due to its reliability in dirty conditions. I have not yet put that theory to the test but one day when I feel like getting dirty I’ll go get wet cold and dirty just to see how they both do and I’ll post up a down and dirty report. So, for most situations the Colt’s weight and ergonomics make up for the recoil in getting back on target and so it wins this bout. Just think how damned awesome the SIG556 would be if the ergonomics were that good. That is my new wish… a SIG556 with a shortened lower receiver and on a diet. That carbine would be awesome. By the way, if I had more experience with my AK-101 it might very well win over both of these for CQC, but I'm not near proficient enough with an AK to take one into a firefight (that is not to say that if that is all I had access to that I wouldn't use it).



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sig556withta11acog551hau.jpg
 
The new Sig Classic series has push out takedown pins front and rear like the AR.

I have both an AR-15 and a SIG 556. I trust my AR completely as I don't have a lot of time with the SIG, but I've had no malfunctions with either and I like both platforms for different reasons - the AR for familiarity and the 556 for design and reliability.

If this is your first black rifle, I'd almost recommend you get the 6920. But the 556 might be harder to get than an AR if something happens politically and people start panic buying like crazy again.

The Colt will always hold value.
 
I love my Sig 556 ER, after putting around 80 rounds through it and cleaning it every 15 to 20 rounds its as smooth as silk. Very little recoil and so far I can get about a 1.5 group at 100 yards using a cheapo 3-9x42 tactical scope. Here is a picture of it with the Olight Ultimate Warrior Package that includes a silent pressure switch, a very nice set-up. Does anyone have pictures of their Sig 556 with a laser mounted?
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