[SHOT 2026] HM Defense Peak Pressure Reservoir and Booster System

At SHOT Show 2026, HM Defense unveiled a new patent-pending barrel technology called Peak Pressure Reservoir and Booster System. This technology is advertised to increase projectile energy and efficiency while reducing unwanted side effects like noise, flash and barrel heating. According to HM Defense, it offers greater operational flexibility, making existing weapon systems more effective without the need for larger, heavier or entirely new systems.

This new barrel design incorporates a series of annular chambers cut in the bore that result in the above-mentioned effects. It consists of two parts: the Peak Pressure Reservoir, which is a chamber right ahead of the neck of the cartridge/chamber and the Booster, a series of annular chambers closer to the muzzle.

Here are the lists of features and advantages of these two technologies as specified by HM Defense.

Peak Pressure Reservoir (PPR)

• Maintains peak pressure with excess propellant charges.
• Increases energy/muzzle velocity.
• A short barrel can perform like a longer barrel.
• Maintains peak temperature/pressure when compared to excess high temperature/pressure systems.
• Increased longevity of components when compared to excess high temperature/pressure systems.
•  Applicable to weapons that fire a projectile with propellant energy, cased and caseless, smooth or rifled bores.

Booster System

• Conserves lost muzzle energy.
• Lowers muzzle blast.
• Lowers exit temperature.
• Lowers exit sound signature.
• Increases muzzle energy and velocity.
• Increases range.
• A short barrel will perform like a longer barrel.
• Eliminates additional friction loss associated with longer barrels
• Applicable to weapons that fire a projectile with propellant energy, cased and caseless, smooth or rifled bores.

HM Defense is also developing a new anti-materiel rifle cartridge called .50MAX. The new cartridge has a larger case capacity than the two most popular 50-cal heavy machine gun / anti-materiel rifle cartridges, the .50 BMG and 12.7x108. The case length of the .50MAX cartridge is 4.37” (111mm), so its metric designation will be 12.7x111. The cases of this cartridge are one-piece CNC-machined out of 7075 aluminum. Making the cases by machining is claimed to provide a more precise and uniform internal case volume to reduce the muzzle velocity deviation. The use of aluminum results in a 62% lighter case weight compared to brass.