Rusty, I am drooling all over that 5 inch suppressed upper... it makes me think of a ruger mk2 bbl on an AR "frame". LOL
Could a person use an AR pistol lower to mount that short of a .22 upper without a tax stamp? What if they owned another AR was not SBR or pistol? Would they be screwed on "intent" even if they never mounted the short .22 upper on the rifle lower?
I had this upper on a pistol lower while the stamp was being processed and my opinion of AR pistol configurations is that they are pretty much worthless.
As it turns out this little rifle actually works really well and is capable of "combat" accuracy out to 150 yards with bulk ammo. To be honest, if I was going to build another rifle like this, I would get a Nordic upper with a somewhat longer barrel. I've gotten a chance to shoot a couple different setups from Nordic and have been very impressed on each occasion.