The newcomer to airgunning- and a lot of veterans- can be confused by the vast range of pellets available today. With all the different shapes, weights and materials available, how can you possibly choose the correct pellet for your gun? It may be easier than you think. There are really only four significant characteristics we need be concerned with: Diameter, mass, shape, and consistency.
Diameter: Suprisingly, airgun pellets of a nominal size (say, .177) may vary tremendously from one maker to another, or even between pellets from a given maker. Some of this is due to the use of old, worn, dies at some of the older makers, but some is just plain puzzling. I tested a tin of copper-flashed, pointed, RWS pellets some years ago that were so loose they’d fall out of the breech of a break-barrel gun if you weren’t careful in closing it. Pellets like this are not going to give anthing remotely resembling good performance. A pellet should fit snugly in the breech. Beyond this, it’s possible to improve accuracy by finding the ideal diameter from a given pellet, and adjust that by sizing pellets; we’ll leave that for a future article.
Consistency is obviously a critical factor. Some of the cheaper pellets out there vary tremendously from one batch to another as well. (That’s one reason Field Target shooters flocked to Crosman Premiers- every box is marked with a designation of which master die was used to cast that batch. No suprises that might come from switching form die #1 pellets to die #2 pellets mid-match!) The cheapest Chinese pellets were notorious in the regard- casting imperfections led to pellets that varied so much from one to another in weight and shape that you sometimes wondered if you were looking at a box of pellets or deformed fishing weights. A lot of the older British designs suffered from this as well- some companies were using the same dies for 20 years or more.
Mass is the next factor to consider. Airguns are resonant systems, and will perform optimally with pellets of a certain mass. With spring guns, it’s important to find a weight that will maximize energy transfer from the spring and piston to the pellet and the column of air propelling it. Too little mass, and the piston will slam against the front of the chamber, transfering energy that should have gone into the pellet into the gun instead. Too much, and energy ends up being transferred back into the spring and piston.
Pneumatic guns are less sensitive to pellet mas, but there’s still a critical range that works best. With too light a pellet, the pellet is expelled before the energy in the gas has all been transferred to the pellet; the result is reduced power, and a large amount of escaping gas that can upset the flight of the pellet. Too heavy a pellet, and energy available in the expanding air column starts to decline before the pellet has left the barrel. That, and the longer the pellet spends in the barrel, the more likely it is to be deflected my movement on the shooter’s part.
The best way to select the ideal pellet mass for a spring gun is to use a chronograph, and compute the muzzle energy- not just the velocity!- for a wide range of pellet weights. Where the total energy is highest, the gun will be performing optimally. From there, use accuracy tests to refine your selection. Sometimes best accuracy is obtained with a pellet that may not deliver the highest muzzle energy.
Shape is particularly confusing given the dizzying variety of pellets designs on the market. But in reality, there are only three basic designs: Flat (wadcutter), round nose, and pointed nose. Wadcutters are designed for punching paper- that’s it. They’re not very aerodynamic beyond 15 meters, and are generally too light for use in most of the guns sold for field use today- although they can be good for plinking at moderate distances in low-powered guns like the Beeman R7.
Pointed pellets are essentially useless for airgunners. The pointed shape is suboptimal for subsonic flight- just look at any aircraft designed for flight in that region- and many of the popular pointed pellets, like the Jet, were designed for very low powered guns 30 or 40 years ago. They don’t penetrate any better than do round nosed pellets of similar mass and hardness, despite some anecdotal claims to the contrary. One of the most popular pellets, the Beeman Silver Jet, was actually designed for very low powered pump pneumatics around 40 years ago, and the design seems to be more about style than any ballistic concerns. It’s far too lightly constructed and low in mass to be used with a gun producing much over 5-6 ft/lbs, and the pointed shape is high in drag. In a high powered airgun it will be severely deformed on firing.
Round nose pellets are idea for field use, whether plinking or hunting, and most of the newer designs are of that style. They have optimal low-drag profiles for subsonic flight, and concentrate mass forward for better stability and penetration. Unless you’re punching paper targets, these should be your first choice.
What about hollow pointed pellets? Well, aerodynamically they’re really round-nose in behavior, and of questionable use. Pellets don’t “expand” in the way that firearms bullets do- there’s just not enough energy there. Some will deform more easily than round nose pellets, but that’s not necessarily useful; in deforming, they will penetrate less. The careful airgun hunter always goes for a head shot, and accuracy and penetration are the critical factors there.
I have a dizzying variety of pellets at home, the result of thirty years of airgunning and my time with American Airgun magazine- they did send me a lot of pellets! But 95% of the time, when I reach for a box or tin of pellets it’s either RWS target wadcutters or Crosman Premiers. Both have a very high degree of consistency, and most of my guns are sighted in for one or the other. This isn’t to say that my airguns might not perform as well- or even better- with some other pellet, but that these two seem to provide as much accuracy and performance as anything else I’ve tested.