Derek Fuller in his book "The Definitive Guide to Muzzle Loading Pistols" makes a very good point.
Whilst the European copies may work quite well under relatively light loads of black powder, the same can't be said of the originals. In particular the Remington which was designed for full chamber loads and has a short rammer. This may not be long enough to push the ball down onto the powder, without the use of wad or filler, leaving a dangerous void behind the ball and an uncontrolled "burn."
Whether this was the case, or if an overload of Pyrodex or nitro was used, I don't know yet as we're waiting for the gun to be returned. Incidentally Tac, it's the H & S Executive and not the police that have the gun at the mo.
As soon as I know more I'll post it because we all should be able to learn something from incidents such as this.
Jim