Disclaimer: This hop unit is designed to be used with a shorter bucking. We recommend the pre-cut Retro Arms Hop Up Bucking. If you purchase another type of bucking, you will need to trim down the length of the bucking sleeve for it to work with this hop unit.
Retro Arms M4 Hop Up Chamber, produced from EN AW 2007 and EN AW 7075 aluminum. Designed to allow precise adjustment in 2mm range with step of 0.01 mm. Chamber is compatible with Retro Arms gearbox but will also work with standard gearboxes. We please we cannot guarantee precise fitment with other gearboxes.
Hop up nub is integrated into press lever, preventing the nub from falling out during assembly/disassembly. Hop up C clip is not included but existing clips will work. We also offer the Retro Arms M4 clip as an available purchase option.