VFC MP5 Hopup Arm and Nub V2 vipertech I would highly recommend utilizing

I would highly recommend utilizing HPA with this recoil spring as I have done zero testing with regular propane gas

To give you potentially essential information I measure each catch several times and write down the exact height of the catch surface on packaging

please note that the compression part of the spring should be connected to the nozzle pin while the tension part of the spring should be connected to the rear assembly that gets screwed into the back of the bolt

Cap only comes with combo package

(helps to close receivers that previously needed to remove the pivot pin)

VFC MP5 Hopup Arm and Nub V2 vipertech I would highly recommend utilizingThis arm provides more consistent hopup tension on the bucking for more consistent BB backspin. 7075 anodized aluminum. Rubber Nub. This new version is CNC machined rather than 3d printed. This hopup arm allows for the use of a rubber nub which will greatly improve your hopup consistency!