Why US Marines Preferred Their 'Obsolete' M1 Garand Over Captured Japanese 'Advanced' Type 100 SMG Power Over Speed: Why Marines Kept Their Garands 🌴 Why did US Marines in the Pacific ignore captured Japanese Type 100 submachine guns? The answer was raw stopping power. While the Type 100 fired the anemic 8mm Nambu round (just 242 ft-lbs of energy), the M1 Garand delivered a massive 2,656 ft-lbs with its .30-06 cartridge. At the Battle for Henderson Field, legends like John Basilone and Mitchell