THEORETICALLY THE PRESSURE COULD BE LOW ENOUGH TO HAVE THE CASE WALLS AND CASE HEAD BE SEPARATE, LIKE A SHOTSHELL
THAT WOULD EASE THE PROCESS GREATLY
CASE WALLS COULD BE COPPER TUBING DRAWN OR PRESSED OVER A MANDREL, CASE HEAD COULD BE CAST OR MOLDED FROM EPOXY OR MOLTEN ALUMINUM OR COPPER
THEN THE TWO COULD BE PRESSED TOGETHER OR GLUED OR SOLDERED