Re: Sig556 add-on advice
Don't really want to suggest optics unless it's a Eotech XPS or Aimpoint, high mag to me for this particular gun is pointless. due to the skinny barrel, long stroke gas piston and 1:7 barrel. 55 gr patterns are 4"-6", going with heavier bullets (69-77)will bring it down to around 3" @ 100yrds. Using a high manification scope will only frustrate you seeing the pattern (not groups). I called Sig on the accuracy and they said it's within spec (3"@100 yards... what ever happend to 1.5" @100 yards as advertised early when the rifle first came out).
Stocks:
I did change mine over to the CTR stock though a better option is the UBR stock the weight balance the gun out, I would stick to the Diopter sights and Sig fixed. I have hae samson on mine but had to settle on a AR BUIS.
Other than that, enjoy the gun, very well designed and clean shooting, probably the best 223 AK pattern rifle you will ever own. Very reliable and well made.. you just have to sacrifice on the accuracy