The purpose of the winter trigger is simple, the up-sale that pretty jeep needs an undercoating. it would be a shame if the road salt rusted the floor pans
But more serious winter means gloves and that means trigger guards. a winter trigger allows you to shoot your gun without taking of gloves.
Goof for any gun from smgs to rifles and machine guns. this brings up the idea of real non rpg non call of duty gun upgrades.
Winter canvas because as metal stamping became common metal gets hot and cold. Canvas barrel guards and now canvas stock guards.
Article about a self-made preheater in the magazine “Von der Front frdie Front” (Of the front for the front) in May 1944. 