All the while, that pellet is being buffeted by the sonic wave it creates, then the dissipation of that wave at the transition point. It’s the perfect antidote for accuracy.
It Gets Worse!
If it sounds bad so far, just wait. A few spring rifles are also able to shoot supersonic if the shooter is willing to sacrifice everything else. A Gamo 1250 spring rifle, for example, launches lightweight .177 pellets at speeds in excess of 1150 fps. They won’t retain much accuracy past 20 yards or so, but they will post spectacular numbers at the muzzle.
The breech of a spring-piston air rifle accepts the pellet directly. When the barrel is closed, it aligns with a transfer port. The air blast coming through this hole can deform thin pellets.
Lightweight pellets used to achieve supersonic speeds have very thin skirts, which is unfortunate because spring guns fire much more violently than PCPs. The sudden hammer-blow of compressed air blasting through the transfer port of a powerful spring rifle breech will blow the thin lead skirts of lightweight pellets against the walls of the barrel, turning an accurate diabolo into a flying trashcan. Add gross pellet deformation to the list of things preventing accuracy.
The PCP is much more suited to produce high speeds. Controlled airflow gives a softer continuous push that doesn’t deform pellet skirts, despite their faster velocity.
What’s So Good About Velocity?
I could cite any number of examples of accurate shooting at low velocity, but the buffalo hunters seem to epitomize it. Their heavy conical bullets left the muzzle at 1200 to 1450 fps, just barely supersonic, yet they racked up mountains of buffalo shot at tremendous distances.
The huge lead slugs they fired were so heavy that the destabilizing effects of the sonic pressure wave were minimized. And most of the bullet’s long flight was subsonic anyway.
Adult air rifles are a lot like blackpowder cartridge rifles, only on a smaller scale. Instead of 500 yards, they are a challenge to shoot at 50 yards, where all of the same problems of wind, spin-induced bullet drift and cant must be dealt with. And, the long-range target definitely tells the story. A heavy pellet that drops 6 inches or more yet lands in the same place every time is far more desirable than a fast lightweight pellet corkscrewing downrange like a knuckleball.
Think of airguns as the model trains of the shooting sports. They allow shooters to enjoy the standard firearm activities at greatly reduced distances. You don’t need high velocity for accuracy, and with diabolo pellets, you don’t want it, either.
Solid Pellets
This discussion seems to beg the question, “If bullets fly better at speed, why not shoot them in airguns instead of these sensitive diabolos?” In fact, solid “pellets” are being manufactured and sold today. I call them bullets, but the makers and dealers still refer to them as pellets.
Solid airgun pellets fly straight and true at supersonic velocities, just as they do in firearms. For example, one Florida experimenter is shooting a highly modified air rifle with 30-grain solid pellets that he says leave the muzzle in excess of 1500 fps He claims to be getting five-shot groups measuring under three inches—not at 100 yards, but at 200! This is the smallbore airgun equivalent of shooting a mile with a modern centerfire rifle.
I’m all for experimentation, but this takes the air rifle into the realm of the .22 Long Rifle. When you shoot a 30-grain solid lead pellet at speeds in excess of 1000 fps, you are really shooting a .22 Short; and, when the velocity increases, it quickly becomes a .22 Long Rifle.
Where a diabolo pellet falls harmlessly to earth at 500 yards, a conical bullet shot at the same initial speed will travel over one mile! So why do it?
One of the greatest benefits of airgunning is range safety. We can shoot and even hunt with powerful guns, knowing our shots will not carry like
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