BBTI - Ballistics by the Inch

ATTENTION: Effective Sept 1, 2020, the BBTI Project is in "Archive Status." No further tests will be conducted, but we will maintain this site and data for the use of the firearms community. Thank you.

Welcome

Welcome to Ballistics By The Inch, or 'BBTI' as people have taken to calling it.

Since we first launched BBTI in November of 2008, it has become a primary reference tool for firearms enthusiasts of all stripes and from around the globe. Our initial research data covered the relationship between barrel length and velocity for some 13 common handgun calibers/cartridges. In response to the phenomenal popularity of the site, we've continued to do testing, and have expanded the data to include an additional 8 handgun calibers/cartridges (and a repeat of the .380 Auto tests with additional ammunition) as well as the .223 rifle cartridge. We've also conducted a major study of the 'cylinder gap effect' on a revolver, involving more than 6,000 rounds fired, as well as a comparison of the performance differences between polygonal and traditionally rifled barrels. As always, all of our data is freely available, though we happily accept donations (see button below left)and would greatly appreciate your tangible support to help us continue the project.

Up above you'll find links to four main pages:

Calibers/cartridges will take you to a list of all 22 different data sets. You can just browse the charts, click on a given ammunition type listed in the header of each chart for a graph of how that particular ammunition performed, or download the raw data for your own use.
Cylinder gap will take you to the results of that study, which used an Uberti Single Action Army clone in .38/.357 mag to examine velocity differences between three different cylinder gaps (0.006", 0.001", and 'flush').
polygonal rifling will take you to the newest part of our site, documenting performance comparisons between polygonal and traditionally rifled barrels in 9mm.
Real world guns will take you to a comprehensive list of all the firearms we used as 'benchmark' comparisons for results obtained from our T/C Encore test platform. You'll also see "review" listed after a number of the guns, which will take you to a review of that particular gun (or a closely related model) over at Guns.com written by Jim Downey of the BBTI team (who is also a writer for Guns.com).

Along the left side there you'll find some more basic information about BBTI.

As we've noted previously, we have no illusions that our data is comprehensive. It is meant to be indicative - giving an indication to the general relationships between barrel length and velocity, or the effect of a cylinder gap, or how polygonal and traditionally rifled barrels perform. It would be impossible (for us, at least) to test all the different ammunition types available, or all the different firearms - particularly so when manufacturers of ammunition and firearms are constantly tweaking and improving their products. So use the data here to get an idea of what to expect, and perhaps as a jumping-off point for your own research.

Thanks for coming by.

Other Resources

BBTI is not the end-all of ballistics testing, just one more component available for the common good. In addition to extensive discussion about ballistics to be found at many gun forums, here are some other great resources pertaining to ballistics testing you should check out. (And if you would like to recommend a site to list here, please send an email.)

BrassFetcher: excellent resource, with an emphasis on bullet performance in ballistic gelatin
The Box O' Truth: testing ammo penetration through various barriers
Terminal Ballistics Research: Specializes in the research of cartridge & projectile performance, using hard data gathered from 20 years of hunting game.

Acknowledgements

We'd like to personally and specifically thank Pat Childs at Fin & Feather in Iowa City, as he not only helped get most of our ammunition and other supplies, he was the brilliant gunsmith who worked with us to make this insane project much more practical. Without his help all of this would have been much more difficult and perhaps impossible. Anyone who uses our data owes him a debt of gratitude.

And thanks to our spouses, who were not just tolerant but enthusiastically supportive of this rather nutty project.

Disclaimer

This project, and all of its results, is only our fault. We (well, Jim K, mostly) paid for everything ourselves, and we did not receive any kind of sponsorship or remuneration from anyone. We did all the work. We used products we were either familiar with, or because they were what was available, and mentioning them by name does not constitute an endorsement of any kind. Furthermore, the data is provided purely for entertainment purposes - to better facilitate arguments over what ammo or caliber or gun is "best." How you use the data is entirely up to you. And if you think you could do better, feel free to spend the money and do the work and publish your own results. Or not. Your choice.