It's an upper for an AR style platform, .22 LR BELTFED!
http://www.lakesideguns.com/webstuff/22uppervid1.wmv
http://www.lakesideguns.com/webstuff/22uppervid1.wmv
actually, one in video looks like .22 WRM, instead of LR....No additional info on website, but they make other guns in .22 LR, .22WRM and even .17. Always wanted a 1919A4...but you can by a real 1919A4 semi auto for about half what they want for 1/2 scale .22 version...Ammo cost a bit different though!