Sig's version of the AR

[jmr40]

What do you think about it? Advantages, disadvantages. How do they compare with Colt and other traditional designs? I'm not really in the market for another AR, but have not really paid a lot of attention to the Sig. Just wondering how they stack up.

[Micropterus]

I have both a Sig M400 and a Colt LE6920. Each has features the other does not. Here's what I have found:

Both have an F marked front sight base.

Both have M4 feed ramps cut before anodizing.

Both are chromed in the same spots.

Both have equal staking on the gas key and castle nut.

Colt has an M16 bolt carrier.
Sig has an enhanced AR15 bolt carrier.

Colt bolt is MP marked.
Sig bolt is not MP marked.

Colt comes with an H buffer.
Sig comes with a standard carbine buffer.

Colt barrel is MP marked.
Sig barrel is not MP marked.

Colt has a standard mag release.
Sig has an ambi mag release.

Sig has a upper/lower tightening device in the lower, the Colt does not.

Sig has built-in sling point attachments in the lower, the Colt does not.

Sig has an extractor support in the barrel extension, Colt does not.

Sig has 6-position mil-spec diameter buffer tube, Colt has 4-position mil-spec tube.

Both have equally bad single stage triggers.

Out of the box, the Sig had no blemishes or marks and was cosmetically perfect. The Colt had various nicks and dings from careless assembly. (Notably around the trigger guard where the rear pin was installed, but also on the delta ring and on various spots on the upper receiver.)

The Sig upper/lower fit is tight. There is not play whatsoever - either in the vertical or horizontal. The the pins can be pushed out with your fingers. There is a lot of slop in the Colt that can be fixed substantially with an accuwedge.

Both consistently eject to the 3:45 position with everything from cheap PMC Bronze and UMC ammo to NATO M193 and M855.

The Sig is proving to be a bit more accurate than the Colt.

If you absolutely have to have magnetic particle tested bolt and barrel, or an M-15 bolt carrier or H buffer, go Colt. Otherwise the Sig is a great rifle. I have well over 1000 rounds through both of them. Both have been 100% reliable.

I like the Sig lower better than the Colt's. I use the ambi mag release quite a bit even though I'm right handed. I also like the upper/lower fit better on the Sig.

[Micropterus]

Here are some BCG comparison photos...

You can see a bit of wear on the Sig's extractor lug from the extractor support the Sig has in the barrel extension.

[Micropterus]

Some more...

[Micropterus]

And a few close ups...


The ambi mag release makes it impossible to use the Magpul MAD lever, but there is anothr brand that works (can't think of it at the moment.)





Here's the devise in the lower receiver that tightens the fit between the upper and lower.


And if you look closely, you can see the extractor support in the barrel extension at the 1 o'clock position (and yes, the chamber and bore are chrome lined, it's just the lighting that makes the breach face look dull.)