Sumitomo NTK-62: A general-purpose machine gun with unusual features

Sumitomo NTK-62 (Type 62)
The Sumitomo NTK-62 is the standard issue GPMG of the Japan Self-Defense Forces. Known as the Type 62 GPMG (Photo: XY)

The Sumitomo NTK-62 is the standard machine gun of the Japanese Self-Defense Force and has some unusual features. It is also known as a Type 62 general-purpose machine gun. It is used on a bipod as the squad automatic weapon and a tripod as a heavy-support weapon.

Design

The Sumitomo NTK-62 is gas-operated, having the standard cylinder and piston below the barrel. The rear end of the piston rod carries a vertical post attached to the firing pin. This post fits into a slot in the breech block, and thus, as the piston moves, it drives the block backward and forwards.

As the block closes the breech, the piston rod continues moving, and a ramp on the end of the rod forces up the rear end of the breech-block until two lugs on its sides are wedged into recesses in the side of the receiver, so locking the breech firmly closed. The last forward movement of the piston carries the firing pin forward to strike the cap and fire the cartridge.

Sumitomo Type 62 on a tripod
Sumitomo Type 62 (NTK-62) general-purpose machine gun on a tripod (Photo: XY)

The quick-change barrel is automatically locked in place so long as the receiver’s top cover is closed. Opening the cover unlocks the barrel so that it can be removed and a new barrel inserted; it also prevents the bolt from rising in order to lock so that there is no chance that the firing pin can line up with the chamber and thus accidentally fire a shot. In contrast, the barrel is being removed or the cover open.

The standard spring-loaded extractor does not extract the spent case; the cartridge is located in the chamber by a spring-loaded stud that presses into the extractor groove below. As the bolt is unlocked, a claw-like arm drops and engages with the cartridge rim, and as the bolt moves back, the cartridge is pulled out of the chamber and ejected.

Feed is from a disintegrating-link belt. A feed arm inside the top cover is driven by the movement of the bolt and pulls the belt access in two steps, corresponding to the backward and forward movement of the bolt as each shot is fired.

Variants

A somewhat heavier version of the Model 74 is used as a co-axial machine gun in armored vehicles.

Technical specifications

Manufacturer: Sumitomo Heavy Industries, Tokyo, Japan
Designed: 1962
Service: 1962-present
Type: gas-operated, automatic
Caliber:  7.62mm
Barrel: 20.6 in (524 mm)
Weight (empty): 23.6 lbs (10.7 kg)
Effective firing range: 1000 m, 1500 m (with bipod)
Rate of fire: 600 rounds per minute
Magazine capacity: belt feed
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