While I used to be a big proponent of the Sig 556, the quality issues coming out have yet to be addressed and customer service is getting worse as Cohen continues to have Sig dig it's own grave.
Problems unique to the Sig 556:
The quality of the components being used to build the rifles is not held to any standard (like they are in a reputable AR-15); QC is non-existent. The screw-on top rail is known to break off. The knock-off furniture is a baby-step above air-soft quality (Sig touts these as "Swiss style" to confuse people). The Swiss style butt stock has durability issues. The gas-ports are often drilled incorrectly (both holes close to same size) or drilled in reverse. Welds on the receiver are occasionally missing. The bolt has peening issues on the front trunion due to improper machining.
Problems with the 55X family:
Safety is difficult to manipulate without massive paws ( i was lucky on this one). Bolt catch/release design is flimsy at best (when combined with crappy U.S. Sig quality, has been known to break). Sling mounting leave a little to be desired. The rifle system is unproven, despite what Sig advocates would like to believe. The tests that are touted as making it the best or most rugged rifle on the planet mean little; As we saw with the SCAR (which was probably the most tested rifle in history), teething issues occur when fielded that do not show up in the tests. All this being said, a Sans-Swiss 551 is miles ahead of the U.S. Sig 556 rifle. If you find a good deal on a real 551, I wouldn't hesitate.
Bottom Line: Any reputable AR-15, even the lowly S&W M&P Sport, is a better buy than a Sig 556 abomination. If you want a piston, buy an Arsenal AK or SCAR.
"Throughout history, it has been the inaction of those who could have acted; the indifference of those who should have known better; the silence of the voice of justice when it mattered most; that has made it possible for evil to triumph."
-Haile Selassie I
Last edited by WayaX; 07-05-2012 at 10:34..