My gfs dad has a sig AR that is very different from the standard ARs. It does not have a charging handle but has a bolt slide on the side of the rifle. It does look pretty cool and is fun to shoot but is very heavy. IS it truly an AR? I just don't think it would be much fun because its not compatable with the wide variety of parts and upgrades we can do with a standard AR. I expect they would be more complicated to build and harder to clean as well. What's with these?
The SIG 556 are more of an AK design, very reliable but not known for their accuracy. The ejected brass will wear the paint off around the ejection port if it is not protected. Many users put velcro around the back of the ejection port to stop the wear.