the ar 7 rifles as which are the protptypes of the one you are refering to have been around for quite a while, and made by a couple of companies, the stock with included rifle parts also floats. it is semiauto, the stock will hold two mags the barrel and the action. i have found it satisfactory to use, but is greatly improved with the addition of a scope on the rifle, the bolt should be partially retracted prior to finally tightening of the barrel nut that will help prevent some common malfunctions of the rifle. you might also look ath the marlin papoos and the springfield armory m7 as two rifles that may be suitable for your use.
alex