Ballistics by the inch: a $15,000 ballistics experiment

Ballistics by the inch is an exhaustive ballistics experiment done by Jim Kasper, Jim Downey and Steve Meyer.

We decided to test thirteen common pistol calibers, each over a range of barrel lengths from 18″ down to 2″, and each using a variety of ammunition (most of it “premium” ammo made for self-defense purposes). In each case we fired three rounds of a given ammo at a given barrel length, recording the velocity of the bullets at 15 feet with two commercial chronographs. If we did not get two reliable readings for each of three rounds, we repeated the process until we did. Altogether we fired over 6,000 rounds of ammunition.

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Thousands of rounds waiting to be shot in the name of science.

They throughly documented the results which are available on the website online and as Excel and PDF documents.

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Jim Downey told me the project cost in excess of $15000, not including the man hours put into it. I asked Jim if they were going to do the same for rimfire and centerfire rifle cartridges, his reply: “Heh – we’re all too exhausted by doing this one . . . but talk to me again in a couple of years. :)”.

These guys have created a great resource that will likely settle some bets, resolve some arguments and be referenced by gun blogs, magazines and books for many years, maybe even decades!

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Hey, thanks for the positive mention – we’re hoping that people find it useful, perhaps even be inspired to do some testing of their own and post the results on our blog to help expand the database available to all.

    Jim D.

  • Barrel length experiments like this used to pop up in gun magazines every couple of years.

  • What these guys have done is 13 different types of cartridges all under the same conditions.

  • K. D.

    There is nothing cooler than shooting rounds for an experiment. 6,000? You are my new hero.

  • Mikee

    I hope (before I go look) that they used multiple barrels of each length, and provided results based on exact bore size and land/groove dimensions.

    I think the cylinder gap on a revolver might vary enough from one gun to the next, or one cylinder to the next, that the repeatability of velocity could be affected.

    I also wonder if the lot to lot variation for ammunition can be a significant contributor to velocity differences….

    All in all, I look forward to reviewing the data