I bought a new SIG 556R that came with a SIG Micro Red-Dot. I wanted magnification so I got a SIG-branded 'CP4' 4X combat scope. I put the red-dot on my AMD65, using a Strike Ind. AK Rear Sight Rail 2. This puts the red-dot sight back low over the action cover. I Loctited all fasteners and removed the 45 degree side rail. This rifle is a TGI re-make and the front sight is canted, to the point that the post was against an ear when getting close to zero, so I had to bend the rear sight over to sight-in with the irons. This is a crummy arrangement which is why I wanted a red-dot. I'm glad to say it worked out great. I sighted it in 1" low at 25 and moved to the 50 yd range. I loaded one round to see where it was hitting, and the shot was only 1/2" off the center. I put the rifle away - that's good enough! The Sight Rail 2 stayed tight and so did the sight screws - this is a great set-up. The other rear sight rails are more robust, not having the cantilevered extension on the rear that is unsupported over the action cover, but I wanted the red-dot low and closer to me. I think its good for range work and home defense. For rough use (truck gun, etc.), you probably would want to use another method.

Any pics? I haven't heard of folks using the Strike stuff on SIGs.

No, I used it on the AMD65. My fault, shouldn't have mixed up the two.

I just cleaned the AMD65 and discovered I got lucky putting the rail on. There's just a little play where it fits between the rear sight flanges so make sure when you 'mock it up' before Loctiting that the gas tube lever will clear it so you can remove the gas tube. Mine ended up closer to the RH side and the lever just barely skimmed the rail. The hole for the through-screw is threaded for the purpose of centering the rail and it has a nut on the other side. That was close to being a genuine screw-up.
A red-dot on an AMD65 with the original wire stock is ideal because you don't need a 'cheek weld' - anywhere you put the dot, no matter where it appears in the lens, is where the bullet goes. Naturally, parallax and the ballistic trajectory come into play, but with the 50 yd zero you're actually pretty good out to 200.

Thanks for the review I've been waiting for someone to post on this option.