"...scabbards for A-4's..." Motorcycles makes more sense than horse mounted snipers. snicker. Cavalry 'snipes' with the main gun of a tank. Mind you, not many snipers using motorcycles to get around. Far more likely to be civilian made for post war, horse back, hunting.
"...heavy machine stitching and the GI style rivets..." Says, "I want this to hold together under extreme use."