This is no reflection on Marines but looking hard at the spigot launcher in Marines photos 1 to 4, makes me think that it could NEVER work - , well not twice! Because while there is a gap between the barrel and the launcher, however small, gas WILL escape and while there is a weak point tranversly across the rotating 'catch', that point* WILL act as a fulcrum point and the launcher WILL bend downwards at that point caused by the explosive power of the gas escaping.

As an example of the power generated by a ballastite cartridge, the act of firing an Energa grenade from an L1A1 rifle off the ground will destroy a plastic butt. Do the same without blanking off the gas plug and see what happens!!!!!!! More to it than that of course.........

Rare beast and we certainly never had one at work - nor have I seen one! PPP as we would say........ That's it........ pi55 poor practice!

*weakness aided and abetted by the small transverse small dia. cross pin used to retain the rotating catch thing..... see it?