Facsimile of short version of 6mm Thermos Bottle. This particular case holds "only" 36 grains of water. While this might be adequate capacity, the first rifle will chamber a slightly longer version that holds a full 40 grains of water and should easily propel 107-grain VLD bullets at 3000 fps from a 28-inch barrel.

Note general form of this unconfined primer blast (produced through a K&M Services tool prepared flash hole) – case head is just visible at center base of flame column. I believe this cylindrical form proves that these gases continue to combust long after production through the flash hole. Approximate dimensions of visible flame 5x25 inches!