rare 7,62x51 Japanese military variation

The Japanese developed their Howa 64 rifle in the late 50's, this rifle used some features from the FAL design, it was also semi and full auto. The Japanese also used a standand 7,62mm case with a 139gr bullet but with a 10% to 20% reduction in performance.

With the reduced loading of the JapaneseAttachment 107985Attachment 107986 7,62mm, full auto fire was greatly improved over standard NATO rifles. The average soldier also did better firing the Howa 64 in the semi auto role too. It was claimed that the standard 7,62mm NATO cartridge could be fired in an emergency situation but continued use would damage the rifle. These Howa 64 rifles were never exported from Japan and any of the cartridges are somewhat rare to find.

My photo shows a early US 7,62mm NATO tracer. and the Howa 64 cartridge with the pale blue tip. Note the head stamp on the Japanese cartridge show only a half NATO symbol indicating a reduced loading

technically that would be 7.62x51 cetme. same projectile and pressure changes. Yayyy

Spain used a 112 gr bullet with plastic insert for their CETME rifle being upgraded by 1958 for standard NATO 7,62mm. The Japanese used a 139 gr bullet for their reduced loading of the 7,62mm which was six years later.

My photo shows (left to right) three Soviet cartridges and a 7,92x40mm CETME cartridge with the 108 gr bullet and aluminium insert. last cartridge is from the UK

Many of the original CETME kits were build-up in the USA and then damaged by shooting standard 7,62mm NATO Attachment 107992

The Cetme Modelo B was chambered in 7.62 Cetme and the Modelo C in 7.62 nato. Main difference between the two models is the C has a heavier carrier and a 50° locking piece where the B had a 60°.
If 7.62 nato is fired in a Modelo B the 60° LP will allow the bolt to open while pressures are still high sending the bolt/carrier flying rearward at warp speed where it will slam into the buffer with such force that the rollers will deploy and dimple the rails.
If this is allowed to go on very long the dimples will deepen to the point where they will trap the rollers and lock the bolt/carrier in the rearward position.
Too much bolt gap will also let the bolt open too soon and eventually damage the rifles reciever as well, even with the correct locking piece.
One of the changes HK made to the Cetme design when Germany adopted the G3 was change the locking piece ramp angle to 45°. This delays the bolt opening just a tad longer further reducing wear and tear along with felt recoil.
I have a custom made 37° locking piece in my Cetme C, it greatly improved accuracy, eliminated case damage, it no longer tosses them into the next county and cut recoil down to somewhere between an M1 carbine and AR in 5.56mm.