Polygonal v. Traditional L&G Rifling ("Glock tests")

This is the newest part of our site.  Firearms today typically use one of two different styles of rifling to impart spin to a bullet and thereby stabilize it for flight.  Traditional rifling uses a number of lands & grooves (L&G) which are cut into the barrel, and is the style of rifling most people are familiar with.  But a number of firearms manufacturers use polygonal rifling, most notably Glock, H & K, and Kahr.

For years people have wondered about the effects of the different styles of rifling, and whether one or the other would offer specific advantages for accuracy or velocity from a given cartridge.  But since many different factors can have an effect on both accuracy and velocity, these discussions have largely remained anecdotal.  We decided to see whether we could generate data as to performance differences between the two styles of rifling as concerns bullet velocity, using our standard chop-test techniques.  The data on this page is the result of those tests.

A few notes:

  • In order to get both a traditionally L&G rifled barrel and a polygonal barrel from one manufacturer, we had to change our usual supplier.  We obtained both barrels from Lothar Walther.  Both barrels were "six groove" (the traditionally rifled one had six lands & grooves and the polygonal was hexagonal).
  • Because we expected the differences in performance between the two styles of barrels to be fairly subtle, we decided to do 10 shots of each ammunition type through each barrel for each inch of barrel length.  At the outset we determined that we would want a minimum of 7 of those 10 shots to be "good" (generate trustworthy chrono readings), or we would add in additional shots to get at least 7 readings.
  • For this test sequence we shifted over to a new Oehler Model 35P Chronograph system.  While we have been happy with the previous brands of chronographs which we have used, this instrument provided a significant jump in accuracy and ease of use, and gave very consistent results.
  • The chops tests ranged in barrel length from 18" down to 3".  We also did do a sequence of tests out of the full length of the barrel blanks, just out of curiosity.  The results of those tests can be found on our blog.

Initially we intended to test both 9mm and .45ACP cartridges for this sequence.  Because of ongoing problems in obtaining sufficient quantities of high quality ammunition, we decided to just go with the 9mm sequence and see whether the results would warrant also doing the .45ACP.  At this time we have decided to hold off from doing the .45ACP tests.

Below you will find the data set for the different ammunition brands/loadings tested.  Each ammunition brand/loading tested is listed across the top, with barrel lengths down the side.  You will also find a graph to compare the trend for the two types of barrel over the different barrel lengths linked to each ammunition at the top.  A note about our selection of ammunition:  for both the standard pressure 115gr and the +P 115gr rounds we chose one jacketed lead hollow point and one solid copper type of ammo.

If you would like more detailed information showing the actual data collected for each test sequence, download the pdf or Excel files, linked on the "Raw Data" page.

Got a question?  Check the FAQ.

Barrel Rifling Results in fps

barrel length Black Hills
115 gr.
JHP +P
CorBon
115 gr.
DPX +P
PNW Arms
115 gr.
SCHP
Federal
115 gr.
Hi-Shok
Federal
147 gr.
JHP
L&G polyg'l L&G polyg'l L&G polyg'l L&G polyg'l L&G polyg'l
18" 1509 1521 1232 1187 1162 1132 1331 1332 1061 1088
17" 1513 1515 1249 1195 1163 1131 1334 1336 1085 1098
16" 1498 1518 1237 1208 1171 1135 1331 1333 1085 1088
15" 1490 1494 1263 1224 1172 1140 1318 1336 1084 1088
14" 1484 1489 1246 1224 1165 1150 1316 1328 1059 1076
13" 1481 1482 1263 1231 1167 1153 1320 1321 1062 1081
12" 1464 1472 1258 1240 1177 1153 1308 1320 1073 1092
11" 1449 1465 1258 1241 1167 1150 1305 1305 1071 1084
10" 1437 1447 1264 1244 1167 1148 1290 1296 1064 1077
9" 1416 1430 1257 1239 1155 1142 1277 1280 1044 1057
8" 1394 1404 1250 1229 1145 1142 1251 1266 1032 1056
7" 1362 1384 1244 1236 1142 1134 1234 1249 1024 1036
6" 1335 1344 1221 1216 1121 1114 1204 1223 996 1025
5" 1291 1300 1209 1204 1100 1096 1174 1186 974 1001
4" 1232 1242 1180 1176 1065 1080 1129 1142 943 955
3" 1153 1155 1129 1131 1027 1030 1058 1069 886 911

Of the real world guns listed below, only the Glocks have polygonal rifling.  The others are all traditional L&G rifling.

real
world
weapon
Black Hills
115 gr.
JHP +P
CorBon
115 gr.
DPX +P
PNW Arms
115 gr.
SCHP
Federal
115 gr.
Hi-Shok
Federal
147 gr.
JHP
Beretta CX4 Storm
16.6" barrel
1469 1252 1184 1330 1057
KelTec Sub2000
16.1" barrel
1462 1303 1201 1318 1080
Glock 17
Gen 4
4.5" barrel
1273 1209 1088 1160 966
Glock 17 Gen 2
4.5" barrel
1289 1218 1109 1168 972
Steyr
M1A9
4.0" barrel
1227 1183 1059 1130 948
Mitchell Arms
P08 Luger
4.0" barrel
1211 1149 1037 1112 924
Steyr S9
3.6" barrel
1154 1151 1045 1096 901
Glock 26 Gen 2
3.5" barrel
1196 1158 1021 1092 910
Boberg
XR9-S
3.3" barrel
1166 1139 1035 1086 907
Springfield EMP
3.0" barrel
1210 1168 1053 1092 904
Rohrbaugh R9
2.9" barrel
1044 1041 908 944 797

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.

image from Wikimedia Commons