during vibration. Harmonic tuning The other solution is to work with the barrel's natural vibration, and tune the components so that the bullet exits the barrel as it is moving the slowest. The simplest approach to harmonic tuning is to concentrate on the ammunition. The internal ballistics of a given cartridge will determine its dwell time, or the time it takes from ignition to exiting the barrel. By experimentally matching the dwell time to the barrel's frequency, the best load for a particular firearm may be found. Similarly, handloading gives the shooter the opportunity to very precisely control the bullet velocity, and experimentally choose the optimum velocity. If it is not possible or desirable to match the bullet to the barrel, there are a number of devices marketed to allow the barrel to be tuned to match the ammunition. There are a number of models of these that work in different ways. One type uses an adjustable damper or pressure bedding point to allow the shooter to find the "sweet spot", where it will do the most good at damping the vibrations that are affecting accuracy. Other tuners work by using an adjustable weight on the muzzle to alter the length of the resonant portion of the barrel, and allowing the frequency to be matched to the ammunition. Airgun powerplants The difference between an airgun and a firearm is the way in which the power to launch the projectile is provided. In a firearm the projectile propulsion is provided by an exothermic chemical reaction, and in an airgun is it provided primarily by mechanically compressed gas, typically either air or carbon dioxide (CO2), though these gases are used primarily for convenience and some airgun variants run on other gases, such as refrigerants like R-134a commonly used in airsoft guns, or hydrogen used in light-gas guns. There are three primary types of powerplant used in airguns: Spring-piston, which uses a spring-loaded piston to compress air within an air pump at the moment of firing Pneumatic, which uses pre-compressed air stored in a reservoir within the gun Compressed gas, which uses a small removable gas cylinder now ubiquitously stores liquid CO2 (Powerlet) Each method has its own advantages and disadvantages, and different areas that can be addressed to ensure consistency. The most powerful systems will produce velocities near or exceeding the speed of sound with lightweight pellets; this, however, is not a