Archer QB78 Velocity Upgrade - XP Tune Kit Increases Velocity

Archer QB78 Airgun Velocity Upgrade
Provides approximately 100 fps velocity increase with any QB78 air rifle.
  The specific design of this kit increases the per-shot CO2 gas volume and that simply translates into higher muzzle velocities. The kit works by opening up two constrictions in the standard factory QB78 design. First, a simple replacement of the breech seal between the barrel and the gas tube. This results in a stiffer and more open gas channel into the breech. Second, a replacement "XP" bolt allows more gas volume behind the pellet as it fires. The results are measurable and usually somewhere in the neighborhood of a 100 fps increase in muzzle velocity.
  Installation Procedure - You will need to disassemble your QB78 receiver, barrel, and bolt assembly in order to install this upgrade. This degree of dis-assembly will require the QB78 Family Workshop Manual for instructions (sold separately). As you can see from the picture, the kit also replaces barrel O-Rings, the bolt probe O-Ring, and includes replacement set screws for the barrel and bolt handle retention. Note: Some localities may prohibit increasing the velocity of an airgun and you will be responsible for compliance with the laws.
  See all of our QB78 accessories, parts, and rifles at our QB78 Home Page.