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The SIG/Sauer catalog continues to expand, now with this new carbon fiber-enhanced M400 and its piston-driven 516 counterpart (not shown.) The free-floating handguard and A2-length fixed buttstock are both fashioned from the cool shiny black stuff . . .

Image: Chris Dumm for TTAG

Yes, $2100 is real money, but street pricing should bring this down to the ‘maybe someday’ price category. Which isn’t bad for a SIG, after all.

You can instantly tell that the carbon fiber M400 is lighter than a standard AR, but exactly how much lightness does that carbon fiber (and your extra dollars) buy you?

Good question: the product tag doesn’t say. The SIG rep didn’t know. And I don’t generally bring my own product scale to the SHOT Show.

SIG is also shipping M400s and 516s with carbon fore-ends and non-carbon telescoping stocks, but they’re perceptibly heavier than the all-carbon stocked versions. Which seems fairly pointless to me, but YMMV.

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  1. It shoots a .22, but my SKS shoots a .30 cal bullet. Does that mean my Norinco SKS is worth 4200.00?

  2. they DON’T know the weight? what the heck. We’ll make this ultralight rifle, but we don’t know the weight.

  3. I’m looking at my de-milled M16A1 next to me. It’s from Vietf$&@ingNam. Seriously. I’ll be getting my new M400 at government speed. I was supposed to get the damn thing a year ago. Also, my body armor is expired. Anyways, I’m looking forward to the new hardware. I wish I could just use one of my personal ARs. Ah, well.

    It should go without saying that I’ll be getting the regular M400 and not the fancy carbon deal or the piston 516.

  4. So now instead of getting carbon fiber into just your hands and forearms, you can get it into your face as well.

    Yep, that sounds like a whole lot of ‘win’ right there.

  5. I recently got my hands on a Sig 516 with the Carbon Fiber hand guard and the standard Arc Defense collapsible stock. I also happen to own a regular Sig 516 (which will be up for sale on Gunbroker very shortly). I’ll weigh the two and give you guys the number. Couple of things to keep in mind on this – the new carbon fiber model dispensed with the bayonet lug to fit the carbon fiber hand guard (probably not a big deal for most people, but worth mentioning if you like bayonet mounts). Also, the new models use a 2 stage match grade trigger versus the standard 1 stage military grade trigger used in the standard 516. Price difference over the standard model is just south of $500. I’d expect to see the M400 listed above at a street price in the neighborhood of $1,700 once supply catches up to demand. Seems a bit costly for a DI gun to me, but your MMV

    • Ok, got it on the scale at home. “old” style 516 clocked in at 7.3 lbs in stock condition. New carbon fiber version is 7.5 lbs.- a gain of .2 lbs. Granted, my version has the Arc Defense collapsible stock rather than the carbon fiber one, but it only weighs .65 lbs, so unless that carbon fiber stock has a negative gravity field, the carbon fiber version of the 516 is not going to weigh much less than the normal 516. I’ll do a review on it in the future and weigh the various parts.

  6. I do love ARs. BUT NOT a all plastic AR. It will be too flimsy and breakable. Proves SiG is bankrupt in ideas we had almost all polymer ARs before they don’t last in popularity long.

    • Well, first of all, only the hand guard and stock are carbon fiber. The receiver is still aluminum and the other bits that need to be metal (barrel, bolt carrier, etc.) are. Secondly, carbon fiber is not plastic nor is it polymer. It is very light, very strong (and very expensive).

      • Carbon fiber in firearms is the best thing since sliced bread when you want light and durable. Anyone else played with Ruta Locura RPK?

    • It’ll come, I’m sure if the 516 version sells. Sig does need to save something for Shot Show 2015. One thing to be aware of-the bayonet lug on the current 716 would get in the way of the carbon fiber hand guard, so it probably won’t be an upgrade you can do on an existing 716. Not unless you cut it off.

  7. I think you should take another look at the picture you posted with this article. Specifically, the break in the top rail above the gas block. It appears to me to have the same gas adjustment mechanism as the 516. Since the picture showing the specifications of the m400 does not list adjustable gas I think it safe to say the rifle pictured is a 516.

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