Durable Custom M4A1 RIS, 130m/s, AirsoftGuns, BY-051, BI-5181M

Durable Custom professionally upgraded version of the electric airsoft gun M4A1 RIS [BY-051/BI-5181M] with muzzle velocity up to 130 m/s. This is not a standard serial production in China or Taiwan, where it is not possible for weapons to be provided much time and care. Upgrade was provided by our company, which has more than ten years of experience and plenty of satisfied customers.

Identification Durable Custom suggests that the weapon was drawn particularly on high emphasis of solidity and durability of the internal parts of the gun. Configuration requirements for a good performance, healthy rate of fire excellent durability and reliability. This full metal gun is supplied from the latest edition of which has recently processed metal body with functional dust cover. Modern type M4 with metal RIS handguard, tactical retractable stock (6 setting positions) and a removable transport handle, on which it is possible to attach different scopes and red dots.

Gun was fitted with favourite parts available from SHS, which has become a world leader in AEG upgrades. The following components were used..

Complete cylinder set from the SHS:
CNC metal piston head with the bearing
SHS metal cylinder head M4
Polished stainless steel cylinder M4
Aluminum nozzle M16/M4 - 21.5 mm

Stress parts from SHS:
Precise piston with a steel teeth
A set of classic gears - standard (16:1)
Rotary spring guide for the gearbox v. 2

Performance parts from the SHS:
Long motor SHS - Torque
Spring M110
Precision 6.03 mm barrel

And the other:
Silicone Hop-Up rubber system
Delayer clip SHS
Metal Hop-Up set M16/M4
Gilded T-Dean connector
Universal MOS FET switching set - type 3D

Basic metal reinforced gearbox was modified and metal chamber of gun was propped by rubber o-rings, which is intended to prevent premature rupture of the gearbox. This problem is not unco mmon for homemade upgrades and weapons mass-produced in China or Taiwan, with a strong spring. The weapon is equipped with a M110 spring and inflict cylinder set and good alignment performance of up to 130 m/s is achieved. The weapon is luxuriously equipped with low resistance wiring and silicon MOS FET switch which is absolutely necessary with strong springs, but often manufacturers and retailers underestimate. The package does not include charger or battery, we recommend to order types. See recommended accessories tab. The pack is supplied with tactical sling, sling swivel, cleaning rod, Wind Up Hi-cap Magazine 300rds, tactical grip, 2pc covers on RIS rails and box AN/PEQ 2 .