The Rob Allen Vecta Mechanism is molded from PA6 30% GS glass filled Polyamide to handle the power needed to hunt large bluewater fish. External shrouds and an internal barrel spigot increase strength at the critical barrel/mechanism interface. Apart from safety considerations, any flex in this area reduces accuracy. Internal webs at several places in the mechanism are designed to spread loading away from high stress areas. All load bearing pivot pins as well as the sear are manufactured from solid stainless steel. The rubber overgrip is clamped in place by the cheekplates to prevent twist on firing. The spring loaded line release cam returns to position after firing for ease of loading. The loading butt will most definitely make your life easy when loading your Rob Allen speargun.