Ballistics by the inch

There’s more there than meets the eye.

One of the things which I have found to be very rewarding concerning our BBTI project has been the way some people have done more than just look at our data. Yeah, just checking our charts and graphs is informative, but for those who take the time to get into the actual data, there’s more there than meets the eye.

Here’s a good example, taken from a nice blog post at the Handgun Club of America:

Think your .40 S&W round is plenty no matter what barrel length you’re using? If you’re using Cor-Bon’s 135 grain JHP, you’re losing a whopping 100 fps per inch (103 to 138 fps) between a 5-inch barrel and a 3-inch tube.
This type of data is there, but you still have to work it out on your own. The good news is that you can directly cut and paste their data tables into a spreadsheet like Microsoft Excel. That allows you to crunch your own numbers if you’re familiar with spreadsheets.

In preparing this article, I used Excel to help analyze some of the data. Since we’re handgun oriented, I focused on the two to six-inch barrel figures. When I looked at .38 Special data, some intriguing things stood out. Something unexpected.

It seems that the losses when dropping from a 4-inch gun to a snubby 3-inch or 2-inch are much higher than losing an inch between four and five inches. In fact, for the ammo listed, the drop from a 4-inch barrel to the shorter barrels was the highest loss of velocity. This indicates that revolver cartridges are optimized for 4-inch and longer barrels.

As I told the author of that post in an email, this is *exactly* the reason why we made all the data available. Call it a crowd-sourcing strategy if you will. And while I think it is great that we’ve had over a million hits, it is probably more important for the long term that we’ve had some four thousand downloads of the data files.

Cheers!

Jim D.

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July 13, 2009 - Posted by | Data, Discussion., Links

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