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.

Cylinder Gap Test

Note the aberrant data point for the 16" no gap.  As with the previous ammo, all the data collected for this point would be consistent with the next ammo in line (the Buffalo Bore .38 special rounds).  We suspect that we just grabbed the wrong box of ammunition for this one point.

barrel length Black Hills, .357 magnum, 158 gr. CNL
.006" cylinder gap .001" cylinder gap no cylinder gap
18" 928 942 957
17" 888 901 941
16" 868 895 1080
15" 872 902 956
14" 878 896 944
13" 854 879 945
12" 841 871 927
11" 821 870 915
10" 828 864 906
9" 815 852 905
8" 814 855 889
7" 820 834 868
6" 805 810 855
5" 793 802 838
4" 765 782 816
3" 741 772 781
2" 688 706 722

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.


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.


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.