SIG in the US has really had a tough time with the 556. Early on, canted rails plagued the rifle, along with the inclusion of an AR stock and an ugly forend that no one wanted. When they finally got around to the 556 Classic, they got close, but no cigar.
They decided to use chincy diopter sights that seemed to be made of pot metal and whose durability remains a large question mark. The Classic retractable folding stock was a step in the right direction, as it mimics a new design from SAN, but they outsourced production to some unknown country and the stock assemblies are weak and often have out-of-spec latches.
At around this same point people started finding that the bolt carrier was peening the trunion, and SIG's response was to grind it all down. Now, they are marketing the 556A1, but they insist on using a horrible handguard rather than something more accurate to the Swiss offerings.
The 556 is a rifle that could have been so much more, had management had the mind to make it a combat rifle and not a high profit margin range toy. A quality AR15 is a much better choice in my opinion, and it wouldn't be one with the SIG name on it.
