So I'm thinking about buying a SIG 556 and I've been reading reviews and pricing them online.  I'm definitely feeling the Sig 556 Classic Swat but read some negative reviews of the rear sight and the rail system.  The new Sig 556 XI seems to clear both of these issues up but I haven't been able to find any reviews or places that even sell them.  Does anyone know how much they cost or have a legit review of one?  Thanks

Last I heard production on the XI was scrapped.

Well, if that's the case then I will probably go with the Sig 556 Classic Swat....

Yea they turned that one into vaporwear.. Scrapped the project but hopefully some of the Ambi lowers they made will end up in 556's

Can't go wrong with the Sig 556 Classic SWAT. I own the newer one, with Swiss stock, and have had ZERO issues. I have ran 500 rounds of Wolf/Tulammo and 600+ of Federal without any cleaning in between and have had no malfunctions. Love it.

How's the classic swat accuracy?

Yeah I'm excited to own one eventually, I like the idea of a weapon that was a piston driven design from its inception.  Plus, I already own a Sig 229 and couldn't be happier with it.  What do you think of the rear sight and the rail system?  I've read that the rear sight is not that great and that the rails become loose after a little bit.  Anyone have experience with this?

The rear diopter is terrible and the rail makes it more front heavy.

I found the optimal setup is to use the MFI irons and the classic Swiss forend.  YMMV.

It's definitely a solid rifle. Great accuracy. More accurate than many of us. Personally i think the rear sight is fine for being stock. I run a red dot optic on mine so it is what it is. The rail system on mine is solid, not loose like the early models. Many people B$%$# about the weight, but lets be realistic here, we aren't going to be carrying it across the Sonoran desert for weeks lol. If you think it's too heavy then you should probably hit the gym. Not any heavier than an AR with lights, lazerzzz, vertical grip, optic, BUIS, sling attachments, cappuccino machine, and whatever other silly things people add on to their rifles.

Like i said, i think it's a fantastic rifle. It eats ANYTHING i put into it. With ammo prices going up, i can shoot cheapO Wolf/Tulammo for plinking, while my friends with AR's cry over ammo prices and get JAMS with cheap plinking ammo. (Own high end AR and it too is ammo picky at times lol)

My 556 is a good gun, very (very) reliable, and much easier to clean then my AR. That said mine is only AK accurate (only shoots 68+ with anything approaching decent groups)  and is poorly balanced compared to an AR (my AR weighs about a pound+ less then my classic,  mostly from the front end).

The folding stock is handy if you have a crowded gunsafe like me :).

Called Sig the other day to ask about the xi, been waiting to get one.   They were supposed to be ready late august, according to Sig early this year.  The guy said to look for them first quarter of 2013.....  read in previous post that they might just do the ambi lowers at some point?    I bought a 516 instead of waiting any longer, very happy with it!

Indeed, the XI model has been put on hold..Ambi lowers may be available for individual sale. More news at SHOT 2013.