by B.B. Pelletier
As I write this report, Edith is sitting on the couch, reading and approving customer reviews of airguns. It’s a lazy Sunday morning, and we generally try to work on things that are easy on such days. She just made this remark to me while reading another customer review, “People want powerful hunting air rifles that cock with 20 lbs. of effort or less. Isn’t that called a precharged pneumatic?”
That was what came to my mind the minute she announced what people want. But experience tells us that it isn’t what’s on the new airgunner’s mind. They want a spring rifle, because they want nothing to do with all the extra stuff that’s needed to keep a PCP running. They just want to cock the gun, load a pellet and shoot. And many of them wonder why this springer can’t be a repeater, as well.
The question that’s often asked
Surely “they” could make a powerful spring-piston air rifle if they wanted to. All they have to do is make one that will go at least 900 f.p.s. [or whatever number seems best to them] in .22 caliber with real-world lead pellets and cocks with 20 lbs. or less. If they would make a rifle like that, I would be first in line to buy one.
Don’t you think “they” have been busily trying to do just that for the past 100 years? From the first moment someone cocked a spring-piston rifle (or pistol) that was a couple of pounds too heavy for them, they started thinking about designing exactly the rifle our hypothetical new airgunner has requested. And they haven’t done it, yet!
But there have been several good attempts. John Whiscombe, for example, broke the cocking sequence down to two or even three pulls of the underlever to cock his dual-opposed piston rifles. Owners of his rifles have not one but two coiled mainsprings to cock; and their efforts, while not quite doubled, have to be increased significantly. Which is why Whiscombe broke the cocking effort into two and even three strokes of the lever. The gun cannot be cocked with fewer strokes. If you try, it will remain in a limbo of a partially compressed set of mainsprings that cannot be relaxed, because they’re held in check by the safety mechanisms. So, a Whiscombe owner can’t cock his JW80 just two strokes for reduced power. It’s three strokes or nothing.
Rutten of Belgium used a small, high-torque electric motor to cock their spring-piston rifle with just the push of a button. Wonderful, you say, except now you’re tethered to the power grid, because the rifle cannot be cocked any other way than by its motor. And when you do push the button, prepare for the sound of an impact wrench for a couple seconds, because that little motor raises quite a ruckus! That rifle sold under the Browning name several years ago, and the reception, once people saw how it actually worked, was chilly at best. So much so that there are still a considerable number of Browning-trademarked new-old-stock rifles that float to the surface every so often, as yet another person wonders, “Why not?”
One approach that did work well is employed by Weihrauch in their HW45 air pistol that also sells under the name Beeman P1. The way it works is that you cock the barrel to the first detent (sear catch) for low power and to the second detent for high power. The cocking force remains approximately the same for both power levels. All that’s different is the length of the piston stroke. It works very well, and I wonder why manufactures are not using it on a rifle today. What’s apparently lost to many airgun manufacturers is that the power of the mainspring contributes very little to the power of the gun. What matters most is the piston stroke. Many springs do stack (increase) in force the farther they’re compressed, but that’s not a universal rule. It’s possible to make a spring that provides a near-uniform force throughout its compression, as Weihrauch has done in the HW45.
Back to the question
We’re discussing why nobody makes a powerful spring-piston air rifle that also has a very light cocking effort. This is a question that many new airgunners ask, not realizing that physics stand in the way. A pellet fired from a spring-piston gun produces only a fraction of the power generated by the mainspring, so that’s the limiting factor. Making the mainspring more powerful is the brute-force way of making a gun more powerful, and it’s the practice that’s in vogue today.
What about a gas spring?
One question that often follows the main one is why wouldn’t a gas spring (gas strut, gas ram) work? To understand why it wouldn’t, you have to shoot a gun that has one. Gas springs exert their full potential from the instant you start cocking them. So, instead of a gun that requires 34 lbs. of cocking effort but starts out at 15 lbs. at the beginning of the cocking arc where the leverage is poorest and you’ll need all the help you can get, the gas spring has 34 lbs. of effort right from the start. Gas springs are never easier to cock than coiled steel mainsprings — they’re always harder, or at least they’re perceived as harder because of how they work.
Where does that leave us?
If you want real power from a pellet rifle and you also want the rifle to be lightweight and easy to cock, the precharged pneumatic is the only way to go. No spring gun ever made can keep up with a PCP in the weight and ease of cocking departments. A Benjamin Discovery weighs just over 5 lbs., yet in .22 caliber it puts out the same power as an RWS Diana 48 that weighs 3.5 lbs. more and cocks with 10 times the effort. If you’re a regular reader of this blog, you already know about the AirForce air rifles, some of which will produce as much muzzle energy as a .22 short, with long-range accuracy that not even a $3,000 Olympic target rifle can match.
My message to new airgunners
The question that you have asked is the same one that’s been asked by airgunners for decades. It’s not that airgun manufacturers have overlooked anything or that they’re holding back, like the inventors of the 100-mile-per-gallon carburetor did in the 1960s. They’re stuck on the physics of the problem. You can’t get more work (foot-pounds of energy) from a shot than the force that’s put into the shot. With a spring-piston airgun powerplant, you’ll get significantly less energy out than you put in.
Can things be done to reduce the cocking effort? Maybe. Has everything been tried? Perhaps not. But if you want to get the greatest power from a light air rifle that cocks easily, you definitely want a PCP — not a springer!