That's probably it, then.
This link says it's a .44 though...
"Starting envelope for the revolver rifle is a Ruger caliber .44 Magnum Super Redhawk revolver. The crane/cylinder assembly is essentially the same. All stainless steel components have been finished by the black-oxide process."
"The factory barrel has been replaced by a four grove, 30 caliber barrel, 10 inches in overall length, with a right hand rifling twist of one turn in 9 inches. The front cylinder gap is adjusted to a maximum of 0.005 inch and a minimum of 0.003 inch."
"This is an exceptionally fast twist for a bullet weighing only 145 grains. However, the muzzle velocity is only 1,025 fps. The twist is required to stabilize the flight path of such a light weight projectile moving at such a reduced velocity, and to provide the necessary accuracy potential. To further minimize the tendency of the slow moving projectile to yaw in flight, "driving" or "rotating" bands have been milled into the flat based solid brass bullet in the manner of many artillery shells."
"Screw-turned with a needle sharp point, the bullet is encased in an aluminum piston with a black plastic front face seal. Both are loaded into a Federal .44 magnum case. Powered by an undisclosed propellant of undisclosed charge weight and upon ignition, the piston moves forward a small amount and its beveled face interfaces with the rear end of the barrel to seal the front cylinder gap. A rubber O-ring on the piston seals the case from propellant blow by, so that all of the propellant gas is driven into the sound suppresser attached to the barrel".
Suppression system sounds similar to a Nagant revolver. Odd.