This is taken from a post by Bret Golihew to Usenet.  I'll flesh it out
later...

From March of '94 to Dec '96, Simulated Reality
Products produced the SRP PM-72 LAW and several other types of paintball
shotguns. It wasn't a profitable venture for me and it was consuming all my
time, so I stopped production. I think I had a lot of good ideas and time has
proven that many of my original concepts were valid in their application to
paintball. 
       The concept behind the LAW is very simple- high volume co2 release using
a 3/4" full ported ball valve mounted on a tube. The co2 volume is constant by
the use of 12 grams and the accumulator, or reservoir, is large enough to
prevent high temperture overpressure. I used  4 to 1 ratio for reservoir to 12
gram capsule volume. 
      The LAW, as designed, was capable shooting 20 paintballs at an average of
200 fps with a 4 to 6 foot spread at 75 feet. It was excellent in the role it
was designed for: eliminating hard bunkers and paintball tanks in scenario
games, a paintball version of the M-72 LAW.
       Features included a carry handle that doubles as a rear sight and
mounting point for the valve handle safety, a large rod type bore blocker for
use as a barrel plug, a detachable ram tube for seating the paintball loading
in the barrel, a carry sling, and the corded foam plugs that hold the
paintballs in the barrel until discharge. This plug system eliminated the use
of paper cup sabots and was a substantial improvement.