This one I find interesting: Rhino Arms 12 Gauge AR
All you have to do is swap out the upper on this Rhino AR10 and toss in a new mag and you have yourself a 12 Gauge AR Shotgun.
I have a Saiga 12 gauge now and I love it. But this rig would allow me to quickly swap out the upper on a .308 AR10 and suddenly I have an AR12. The AR10 takes standard DPMS mags and has five and ten round mags available for 12ga.
Can drums be far behind!
--That is a pile of Rock and Roll right there! Can't wait to find the price!