Monday, March 26, 2018

Ballistics by the Inch

I recently ran into an interesting website as I was researching a future purchase, Ballistics by the Inch.

Barrel length in inches on the horizontal axis.  Energy in foot pounds on vertical axis.  Blue dots are standard velocity, 40 grain, lead Winchester.  Red dots are 40 grain CCI Velocitors.  Circled data are two types of .22 Win Mag ammo.  In general, every additional inch of handgun barrel produces an additional 15 foot-pounds of kinetic energy.  Graphic produced by ERJ Inc.
What surprised me is that this is a mix of "real life" revolver and semi-auto data.  From this data, one can conclude that the increase in effective barrel length of the revolver is almost always negated by the leakage between the end of the cylinder and the start of the barrel.

A second conclusion is that another inch of barrel length, in .22 LR handguns, increases the velocity as much as switching from HV .22 LR ammo (advertised velocity of about 1200 fps) to Ultra-HV .22 LR ammo (advertised velocity of about 1400 fps).

The third set of data from the left, the one that is significantly above the trend line, is a Ruger revolver.  Presumably that specimen had a very tight fit between the cylinder and barrel and very little gas escaped.

The first circled data is a Heritage .22 Mag revolver and it does not perform significantly better than .22 LR firearms.  One suspects that the gap between the end of the cylinder and the barrel was excessive on that particular specimen.

If any of my readers have opinions about 4" vs. 6" barrels in the Ruger Mark XX/Browning Buckmark/S&W Victory handguns I would love to hear them.  Also, any recommendations for holsters for "open carry" with secondary retention features for that class of handguns will be much appreciated.

.357 Mag
Graphic from BBTI website
Graphic from BBTI website.

1 comment:

  1. Ballistics will always vary greatly, even within guns of the same manufacture. And the gap between the forcing cone and barrel WILL cause loss of velocity.


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