This is the SIG 552 rifle. I just had to do a post about this gun because of how beautiful it is. I really like the overall aesthetics of Swiss small arms. They look like German weapons with a hint of trademark ugly-cool factor. Its hard to say what it is, but it hits people the same way HK stuff is received. Some people think it's hideous, but some of us just start drooling at the sight of one of these Swiss masterworks.
Operation
This operated off of a long stroke gas piston, just like an AK. Having the operating rod under forward spring pressure attached to the BCG means that there is no recoil spring in the stock. The 552 is therefore equipped with a side folding stock for super compact transport.
Features
This is a select fire (1,3, and full auto) short barreled rifle with a folding stock. It feeds from a 2- or 3- round magazine . The magazine is an AK-esque double stack which locks in and releases with a paddle. The receiver is stamped steel and most of the furniture of polymer, making it quite light. The iron sights are the HK G3 style rear drum and front hooded post. There is an additional 1913 rail for mounting and optic on the top of the receiver.