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This article features a modification-related subject.

The Nerf ThunderBlast, an example of a HAMP blaster.

High airflow manual plunger (HAMP) is a type of plunger system. Unlike conventional direct or reverse plunger systems, the HAMP system does not rely on a spring to actuate the plunger, and instead relies on the user manually working the plunger to fire a projectile out of a blaster.


Most HAMP-action blasters use a direct plunger, sans spring; some HAMP blasters that use a reverse plunger may exist. HAMP-action blasters do not feature the use of a trigger and solely rely on the user's ability to manually work the plunger by quickly and forcefully pumping the blaster's priming handle. As a result, HAMP-action blasters are less mechanically complex than other plunger systems. Since the system relies on the user's ability to work the actual plunger, range and power of the projectile may vary based on how fast the user pumps the blaster. Unlike other air-powered systems that use an air bladder or air tank, HAMP action blasters cannot store their energy and must release it instantly.

HAMP-action blasters usually feature larger projectiles such as Elite Missiles. Most HAMP-action blasters feature a pump-action style of priming mechanism, as that is objectively the most convenient and user friendly priming layout for a HAMP system.


The seal of the plunger's o-ring can be replaced or bedded with electrical tape to increase the plunger's seal. This modification is much more effective on HAMP-action blasters than spring-powered plunger blasters, since it is easier for a user to manually overcome the friction from the increased seal than a spring-powered plunger can; however, it will be much harder to manually pump the blaster after the seal is increased, and may also cause the pump to get stuck occasionally, especially when the blaster is not used for a while.


  • The HAMP system has many different names stemming from its acronym. These include:
    • High airflow manual plunger
    • High airflow manual pump
    • High airflow manual propulsion
    • Hand-actuated manual pump
    • Hand-activated manual primer
  • In theory, any blaster that features a plunger rod-style of priming mechanism can be converted into a HAMP action blaster by holding down the firing trigger, pulling back the priming handle and manually slamming the plunger forward. However, compared to the similar bow firing method, this method of firing is neither practical nor likely to yield longer or consistent ranges.