Explosive Charges

Anybody with an internet connection and the capacity to type can publish any manner of outlandish foolishness these days. Urban legends pique curiosity, with just enough apparent truth to make them feel real. One such claim orbits around the gory risks of running afoul of a revolver’s cylinder gap.

What’s The Problem?

Back in the “old days” handguns were fired one-handed. Military and police handgun training involved extending the shooting hand dramatically, perching the support hand jauntily on the hip, closing the non-dominant eye and blasting away with vigor. Then Jeff Cooper and a few others started really thinking about this stuff and the landscape shifted seismically toward two-handed holds. Nowadays, particle physics isn’t subjected to the sorts of rarefied cerebration as is the art of combat handgunning.

Ergonomics is the study of how machines interface with the human form. As regards firearms, this governs the way we hold our guns. Today, this means you grip your gun firmly with your strong hand while wrapping the support hand around in such a way as to appease the jealous gods of balance, pressure and isometrics. Stated practically, you slide your weak hand way forward, tuck the thumb beneath its stronger sibling, and pinch the gun like you mean it. This puts your weak thumb out into some previously unexplored territory.

None of this matters on an autoloading handgun. There is ample steel completely surrounding the scary bits. However, what about big-bore revolvers? What happens if your thumb comes to rest across the infamous cylinder gap?

A Bit Of Science

A typical .44 Magnum cartridge produces 36,000 psi of chamber pressure. Ignoring a bunch of trivial stuff, for a given pressure the velocity of a fluid is a function of its cross-sectional area. Smaller spaces yield faster flows. A Swiss physicist named Daniel Bernoulli birthed the science back in the 18th century, and his eponymous principle drives such stuff as carburetors, airplane wings and rocket nozzles. What this means, practically speaking, is for the pregnant moment after the cartridge detonates but before the bullet leaves the barrel, hot gas is jetting out of the tiny 0.007″ space ahead of the cylinder at some truly phenomenal velocities. Slip your thumb alongside and foul things can result.

One of my countless gun photographs just happened to capture my Italian replica 1873 Single-Action Army at the very moment of ignition. There is fire coming out all over it. With this as impetus, we embarked on a bit of junk science to prove or disprove the capacity of your typical large-bore revolver to blow your hand to pieces. If ever there was a monster hiding in plain sight for American gun owners, this is it.

There was no academic rigor to our assessment. We just took some white T-shirt material, rigidly secured it around a variety of wheelguns with duct tape, and proceeded to throw a few rounds downrange. The results were indeed illuminating.

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