An under-barrel magazine extension (UPM) is a weapon element that is installed instead of the standard flat nut of an under-barrel tubular magazine to increase the number of loaded 12-gauge cartridges. Installed on semi-automatic and pump-action shotguns of MP type – 153, 155, 133 and other similar models.
Features: The UPM is made of high-strength aluminum alloy, which makes it durable and wear-resistant, and deep anodizing coating increases corrosion protection. A long spring is attached to the UPM to fix the extension and ensure the functionality of the magazine. The product has a ring with a swivel for attaching a belt.
Installation rules: Make sure the gun is completely unloaded and turn on the safety. Unscrew the standard nut by hand, remove the plastic cup, remove the spring and set it aside. Place the long spring in the magazine, put the tensioner on it and tighten the nut until it stops.
Attention! When installing the UPM, keep in mind that the number of cartridges in the magazine should not exceed 10 pieces. The exception is sporting weapons.
The under-barrel magazine extension is available for shotguns: MP-133, MP-135, MP-153, MP-154, MP-155, Remington SPR-453, MC 21-12, Benelli M4.
