Portuguese Army M64 Dilagrama G3 Grenade Pouch

Here its a M64 Dilagrama Pouch Dilagrama its a rifle-grenade device

The Dilagrama m/65 (Portuguese for acronym: Dispositivo de lançamento de granadas de mão - modelo de 1965; English translation: "Device for Launching Handgrenades - Model of 1965") is a device employed by the Portuguese Army that fits G3 Automatic Rifles allowing them to launch defensive Type m/63 hand grenades further than they can be thrown by hand.

The dilagram holder bag arose from the need to carry this grenade launcher in an expedient manner that would allow it to be carried safely and quickly to assemble and use on the weapon.

 It had two compartments, the smallest for carrying propellant and the largest for carrying the dilagram. 

This pouch also served as a makeshift holster for the Parabellum and Walther pistols as an impromptu replacement for the easily rotting leather holsters.

The Dilagrama basically consists of a grenade adapter that fits the barrel of the G3. It is based on the US military's M1A2 Grenade Adapter, a modified M1 Grenade Adapter used with the M26-series Defensive Grenade.

The adapter consists of a 3-pronged bracket for holding and securing the grenade (with the lever held down by a breakaway safety tab on the third prong), the tubular body for fitting to the launcher, and the tailfin assembly.

The Dilagrama is launched with the use of special blank ammunition. The safety tab holding the grenade's arming lever breaks away when launched, arming the grenade in mid-air. Depending on the range, the grenade will then either air-burst over the target or impact and then detonate.