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Whiscombe’s Dual Piston System

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Spring air guns are rugged, reliable, and simple to maintain, but they do have a disadvantage compared to pneumatic guns- as they get more powerful, they get heavier, and larger.  More powerful guns require larger, heavier springs, and heavier pistons- which means more recoil and higher stresses. Spring strength has to be increased not just to propel the pellet, but to move the combined mass of itself and the piston quickly enough to keep lock time reasonably short. There’s a point at which the mass of the combined spring and piston simply makes a gun unwieldy.  It’s difficult to make a spring gun with a power much beyond 22 foot-pounds. But John Whiscombe, one of the true wizards in airgun design, came up with a very clever way of overcoming many of these limitations.

Back in 1987, Whiscombe reasoned that by using two springs, and two pistons, he could increase the power of an airgun without overstressing the parts. And by having the pistons move in opposite directions, recoil would cancel out! Result: A spring air rifle that could achieve muzzle energies of over 30 foot-pounds with zero recoil. The dual-piston system was not original- RWS/Diana used it in the 6G target pistol- but making both pistons active was original. Like the Diana system, the Whitcombe system requires careful adjustment and synchronization to get the pistons moving at exactly the same time. A bit off one way or another and you get a huge loss in efficieny and the recoil returns as well.

About the same time Whiscombe was developing his dual-piston system, Dave Theobald and Ben Taylor of Theoben came up with another, simpler system: Replacing the spring with a cylinder of pressuring gas. Low mass, no metal fatigue, and no overstressed springs. The result was a simple system capable of over 30 foot-pounds without the complexity of Whiscombe’s system.

But even as Theoben’s rifles gained traction in the marketplace, Whiscombe continued making his unique guns. Not only do they have the advantage of zero recoil, but for many airgunners, there’s the simple pleasure of owning a precise, hand-made example of the airgun maker’s art- and owning a rare gun made entirely by hand, and in very limited numbers. If you’re interested in obtaining one of these handmade beauties, you can read more about Whiscombe’s guns here.

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