Years ago I had a friend who collected motorcycles: road racers, enduro bikes, trials machines. If it was weird or cool or exotic, it would wind up in his garage. When I pointed out to him that he could ride only one motorcycle at a time, he said, "Yeah, but there's something to like about each of them."
And so it is with airgun powerplants. There are several different major types of airgun powerplants, and there is something to like about each one. It's little wonder that many shooters own, or have owned, just about one of every type.
The springer appeals to the man who just wants to grab a tin of pellets, a rifle, and go - 'cause that's all you need. Spring-piston powerplants are self-contained, deliver consistent velocity from shot to shot. They use a lever to cock a spring which shoves a piston forward and causes the pellet to rocket downrange. Spring-piston rifles are low maintenance, requiring only occasional lubrication of pivot points and points of wear, and a high quality springer can last for half a century or more with occasional replacement of seals and/or spring. Springers are often very quiet when compared with other airguns powerplants delivering the same level of power.
Springers can be phenomenally accurate, but it generally takes an extremely good shooter to master the forward-and-back recoil of this powerplant and get the highest possible accuracy. In addition, springers demand an "airgun rated" scope. As the power level of springers goes up, the reliability often goes down. Spring breakage, piston head damage, and hard wear on cocking linkages and trigger sears can appear because the powerplant is being pushed really hard.
There are, however, exceptions to the high-power-means-high-wear rule, and there are a few powerful springers available that are truly wonders: high power, easy to shoot, and understressed. One of the nice things about springers is that the barrel is dried on every shot, so you don't have to worry about problems with moisture.
The precharged pneumatic, or PCP for short, might well be described as an instant hero kit because they are extremely easy to shoot well, turning a beginner into a deadline almost instantly. PCPs use a SCUBA tank or high-pressure hand pump to pressurize the rifle's on-board reservoir. PCP triggers are generally excellent, and it is far easier to get high power levels with a PCP than with a springer.
PCPs are generally louder than other powerplants, although some have shrouded barrels for a more neighbor-friendly report. In non-regulated PCP rifles, the velocity may vary with the reservoir pressure. In addition, exceeding the recommended fill pressure may actually result in lower power and velocity. Except for occasional seal replacement, PCPs require little in the way of maintenance.
With a PCP, you need a dive bottle, pump or compressor to keep refilling the gun. With a sporting PCP, you may get 40-60 shoots between refills. With a match gun, you may get as many as 200 shots between fillings. Because moisture tends to collect in the barrel of a PCP, it's wise to lubricate pellets before shooting them. But this doesn't have a huge chore: just sprinkle a couple of drops of Shooter's Choice FP-10 on a tin of pellets, stir them with your finger, and you're done. So, while it's a very good idea to lubricate pellets for a PCP, it only takes a few seconds once you know the trick.
CO2 powerplants are all about convenience and ease of shooting. They use 12-gram cartridges, bulk-filled tanks or the new AirSource 88-gram CO2 cartridges to drive pellets down the barrel. They are recoilless, convenient, sometimes astonishingly accurate and generally easy for the whole family to shoot. Big drawbacks: their performance can drop significantly when the temperature gets below 50 degrees, and when the CO2 runs out, you have to change the cartridge or refill the tank.
In my experience, when you fire a gun that uses 12-gram cartridges rapidly, the velocity can drop by as much as 100 fps as the cartridge cools rapidly. AirSource-powered guns seem much more consistent in their performance. In addition, some of the AirSource-powered guns pack enough wallop to be used for hunting pest control.
If you are into "replica" airguns - airguns that look identical to their firearm counterparts -- or if you want to do rapid shooting with an air pistol, CO2 power is just about the only game in town. In England, where it is virtually impossible to legally own a powder-burning pistol, shooters have taken up IPSC-style action pistol shooting with replica air pistols powered by 12-gram CO2 cartridges.
Single-stroke pneumatics are self-contained, recoilless, and often phenomenally accurate. They require just a single stroke of an on-board pumping lever to fully charge the gun. The only significant downside of this powerplant is that they rarely generate more than 6 foot-pounds of energy, so they generally are not a good choice for hunting, except for small varmints at close range.
Multi-stroke pneumatics are recoilless and self-contained, and both the power and the velocity can be varied with the number of pumping strokes. Multi-stroke pneumatics generally deliver accuracy and power sufficient for small game hunting and pest control. As the name implies, multi-stroke pneumatics require multiple strokes of a pumping lever to pressurize an on-board air reservoir. But once you pull the trigger, the multi-stroke pneumatic must be pumped up all over again.
For personal and professional reasons, I get to shoot 5,000-6,000 rounds through airguns every year, and I can honestly say that I don't have a personal favorite powerplant.
It all depends what I want to do. For long-range, high accuracy shooting, a PCP rifle gets the nod. For Field Target competition, I'll shoot a springer or a PCP, but when my neighbor wants to remove a pest from his garden, I'll usually turn to one of my multi-stroke pneumatics. When it's time to shoot in the local air pistol league, my single-stroke pneumatic is usually picked, but a CO2 replica is the pistol of choice for rapid-fire plinking. But when my brother-in-law and I want to spend a relaxed afternoon dropping targets at medium range, I usually select a springer.
That's one of the great things about airgunning as a hobby - there's something to like about each of them.