The Japanese designed their own rifle to replace the US M1 rifles used by the military forces. The new rifle was the Howa Type 64 (produced from 1964 t0 1988) and had the following
data: weight 9.7 lbs, total length 39 inches, barrel was 17.7 inches long. It is a gas operated tilting bolt action with a 20 round magazine. Full auto is 500 rpm.
Now this rifle was design to use a reduced loading of the standard 7,62 NATO cartridge to produce a muzzle velocity of 2300 fps (this is about a 10 to 15% reduction). The Japanese state that is more accurate for troops to use and better control in full automatic fire.
The Howa 64 could in emergency use the standard 7,62 NATO cartridge but prolonged use
could damage the rifle. These rifles and cartridges were never exported outside of Japan.
the cartridge headstamp shows the Nato circle but only one line to indicate a reduced loading