Precharged All The Way
Easy to shoot, easy to maintain and the most accurate of all airgun powerplants, PCPs – pre-charged pneumatic airguns – have quickly become the darlings of shooters everywhere.
YE OLDE AIRGUN
The PCP may be the oldest type of airgun power plant, yet it is the one undergoing the most development today. Surprisingly, pre-charged pneumatic airguns have been around since the early 1600s.
n the 19th century, there was a huge interest in, often beautifully decorated, pre-charged pneumatic guns, sometimes even disguised as walking canes. This first wave of PCP popularity ran on until the First World ar.
For about 50 years, PCPs went into hibernation to re-emerge in the 1970s. Today PCP technology is applied to the traditional airgun calibres of .177, .22 and .25. Yet recent developments in PCP designs have brought us very high-powered air rifles, some in much larger calibres than the traditional bores. PCP rifles in big bore calibres such as 7.62, .357, .45, .50 and even a few larger ones are offered by more than a few manufacturers.
VALVES AND RESERVOIRS
In general, pneumatic airguns propel projectiles by utilising the energy within compressed air, which is pressurised beforehand, stored in a reservoir inside the gun, and then released through valves when shooting. Pre-charged pneumatic airguns have their internal reservoir pre-filled from an external air source – such as a diving cylinder, or by manual charging with a hand pump – and remain pressurised until depleted after repeated shooting. During shooting, the hammer strikes the reservoir’s release valve, allowing a set volume of pressurised air to be discharged into the chamber, propelling the projectile forward in the barrel.
Depending on the release valve design, PCPs can be divided into two categories: unregulated and regulated. In case of unregulated PCPs, the release valve is held closed by a spring, containing the air pressure in the reservoir. The pressure of the spring is constant, and the working pressure of the air is released, decreasing with each successive shot.
As a result, when the air pressure in the reservoir is high, the valve opens less fully and closes faster than when the reservoir pressure is lower, resulting in a similar total volume of air flowing past the valve with each shot. This results in a degree of partial self-regulation that gives a greater consistency of velocity from shot to shot. Well-designed PCPs will display good shot-to-shot consistency over a long period, as the air reservoir is being depleted.
Other PCP airguns are regulated, meaning the release valve operates within a secondary chamber separated from the main air reservoir by the regulator body. The regulator maintains the pressure within this secondary chamber at a set pressure, lower than the main reservoir's, until the main reservoir's pressure drops to the point where it can no longer do so.
As a result, shot-to-shot consistency is maintained for a longer period than with an unregulated valve and the gun is also able to produce more shots due to reduced waste of reservoir pressure.
Although full-size rifles are the norm, bullpup rifles have grown into an interesting sub-type in PCP designs. With their barrels nearly running all the way to the buttstock, bullpup rifles are the epitome of compactness, combined with the power and accuracy of a full-size rifle.
Although less common than rifles, PCP pistols are also available. Although single-shot PCP air rifles exist, repeaters featuring a magazine and a bolt or cocking lever are the norm. Where allowed by law, PCP rifles firing in semi- or even fully automatic mode are also growing in popularity. These repeating mechanisms are battery or air-powered, depending on the maker.
In the growing PCP market, long established brands are seeing an influx of both completely new contenders as well as major spring/piston brands introducing their own take on PCP airguns. All this increasing competition in the PCP market has brought some quite reasonably priced and competent models, which further enables the industry to show increasing growth.
Diving cylinders, compressors, hand pumps, filler devices… This all may sound mighty complicated at first but it really is not. These are the external devices with which you have to fill up the internal air reservoir of a PCP airgun. Filling up a PCP with a diving cylinder is the most convenient way to go. You will need a fill adapter to make an air-tight connection from the tank to the gun as well as to measure how much air pressure is put into the gun. The diving cylinder itself has a valve that you control with a handle. Simply open the valve and fill the reservoir slowly until you reach the desired pressure level.
Instead of using a diving cylinder to fill your PCP gun, there are also manual air pumps that allow you reach pressure levels up to 3,500 psi, depending on the model. Early pump designs encountered problems of fatigue, warping and condensation. Nowadays quality pumps feature multi-stage chambers and built-in air filtration systems to overcome many of these issues. A manual pump may not be as convenient as a diving cylinder but a shooter with a manual pump doesn’t have to go to a diving shop to regularly fill up his cylinder either.
SHOOTING WITH A PCP
The reason why PCPs have become so very popular is that they are extremely accurate as well as really easy to shoot well. Once a pre-charged airgun is pressurised, all the shooter has to do is load and fire, many, many times, before filling up again with air. This lets the shooter focus shooting straight besides cocking a powerful mainspring or pumping up the gun for the next shot. It doesn't get much more convenient than this. PCPs are also free from vibration as well as recoil, issues that often make powerful spring guns difficult to shoot well.
A PCP handles more like a .22 rimfire than a spring-powered airgun, which makes for much easier shooting. Although pre-charged guns are inherently no more accurate than other types of airguns, shooters find them much easier to use accurately because of how gently they behave. These PCPs are easy to use, consistent, accurate and can be quite powerful as well. Agreed, operating a PCP requires learning new skills, yet the advantages – not to mention fun – these airguns bring far outweigh acquiring a new skill set.