Maruzen M870 Extension Custom Black Version: specs, joules & FPS

Complete specs Maruzen Gas NBB (non-blowback)

Maruzen M870 Extension Custom Black Version, NBB: 0.45 J, 220 FPS, 2,600 g, 6 rounds. Full specs from the official source, with FPS for every BB weight.

Power

Energy · computed0.45 J
Velocity220 FPS67 m/s

Within Italy's 1 J limit

Energy computed from the velocity with 0.20 g BBs, the standard weight manufacturers and shops use to measure FPS.

For information only, based on the source's data for this version. Not legal advice: always check current local law and the version the shop sells.

Technical specifications

BrandMaruzen
ModelM870 Extension Custom Black Version
CategoryShotguns
Power sourceGas NBB (non-blowback)
PlatformM870
Weight2,600 g
Length927 mm
Magazine6 rounds
Hop-upFixed

Weighs 2,600 g: heavier than 67% of NBB replicas in the same category in the database (12 with weight).

Similar alternatives

Same type and category, with similar power and weight.

ReplicaEnergyFPSWeight
Maruzen M870 Extension Custom Wood Stock Version0.45 J2202,600 g
Maruzen M870 Black Version0.45 J2202,550 g
Maruzen M870 Wood Stock Version0.45 J2202,550 g
Tokyo Marui M870 Wood Stock Type0.58 J2502,660 g
Tokyo Marui M870 Tactical0.58 J2502,680 g

Velocity with different BB weights

At the same energy, heavier BBs leave the barrel slower. Expected velocity with the most common weights:

BB weightFPSm/s
0.20 g22067
0.25 g19760
0.28 g18657
0.30 g18055
0.32 g17453
0.36 g16450
0.40 g15647

Theoretical calculation at constant energy (0.45 J). Real-world values can differ slightly with hop-up and replica.

Try other values in the joule ↔ FPS converter →

Data source

The values on this page come from the product page of the shop redwolfairsoft.com, checked on 2026-11-07. The manufacturer does not publish full specs: values may refer to the version that shop sells.

Shop product page ↗ redwolfairsoft.com

Spotted a wrong or missing value? Let us know.

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