I have a TacSol upper, mounted on a Colt LE6920 lower, set up with a Aimpoint T1 and LaRue BUIS. At first light primer strikes were common, but a trip to the factory has it running like a champ.
At first TacSol was not going to use normal FSB on the upper, but use simple gas blocks (unconnected) on the barrel. I have an early proto-type that had a normal front sight. Not marked F, so it'll need a taller post.
On the range it is only given away by the Black Dog magazines and when the ejection port is open.
I secured a decent quantity of Black Dog magazines, along with their loader.
http://blackdogmachinellc.net/I can do about 80% of the drills that I can do with the full caliber gun, at a fraction of the cost. This thing has some future to it.
Next, a GemTech can is going on the front end.