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


barrel length Buffalo Bore heavy, .38 special +P, 125 gr. LV Gold Dot JHC
.006" cylinder gap .001" cylinder gap no cylinder gap
18" 1278 1355 1353
17" 1258 1290 1329
16" 1236 1280 1314
15" 1252 1274 1343
14" 1236 1278 1339
13" 1225 1281 1327
12" 1230 1245 1333
11" 1213 1222 1298
10" 1218 1253 1286
9" 1177 1225 1279
8" 1188 1220 1274
7" 1170 1221 1262
6" 1171 1191 1224
5" 1151 1162 1199
4" 1116 1130 1190
3" 1110 1089 1125
2" 992 1033 1033

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.