Already deemed prohibited I believe.
I would be extremely surprised if that is the case... yes the tubes are prohibited from holding more than five all together, but that doesn't mean that the firearm is a prohibited design just like the SRM 612 wasn't. It's just prohibitively expensive for a terribly neutered design. Almost as bad as a P90, but worse because its not mag-fed for quick re-loads.
I personally think this is more of a case of no one has bothered to try for an FRT because the market doesn't really have a demand for it.




























