Velocity by Barrel Length of Various Calibers
This page will examine barrel length to velocity differences for various calibers. We'll mostly stick to common calibers, but others will likely be added as well. But first, the concepts will be discussed below. The data will follow.
Contents
How Does Barrel Length Affect Velocity?
It is well-established fact that the length of a firearm's barrel will affect velocity (and therefore muzzle energy and even trajectory) to varying degrees. This is because the longer the propellant has had time to burn, the more of its maximum effect on the projectile can be utilized. Otherwise, energy will be wasted and propellant will likely burn off outside the barrel.
Why Does Barrel Length Affect Velocity?
This can depend on a number of factors, such as burn rate of the propellant, bore diameter, and probably others as well. The same caliber gun with the same barrel length could even show different results. For example, two revolvers of the same caliber and barrel length could differ in their amount of cylinder gap, allowing one to waste a bit more energy than the other. Likewise, semi-automatic or fully-automatic firearms will typically have lower muzzle velocity due to some of the propellant's energy being bled off into the gas system to work the action, and this can vary by individual firearm as well. Some guns, such as Heckler & Koch's integrally suppressed MP5SD are actually designed to bleed off excessive gas pressure to make sure any rounds they fire will remain subsonic! However, that is an edge case and can mostly be ignored as it pertains to the topic at hand.
We'll note various barrel lengths and load data on various calibers, from various sources.
.22 Long Rifle
Data for .22LR shown below is sourced from Ballistics by the Inch. A number of popular loads from major manufacturers were tested.
Barrel Length | CCI 27 gr. CPHP | CCI 29 gr. CPRN | CCI Stinger: 32 gr. CPHP | Remington Yellow Jacket 33 gr. (truncated cone, CPHP) | Remington Viper 36 gr. (truncated cone CP) | Remington Golden Bullet 36 gr. CPHP | CCI Mini-Mag 40 gr. CPRN | Winchester Super X 40 gr. RN | CCI Velocitor 40 gr. CPHP | Aguila Sniper SubSonic 60 gr. LRN |
---|---|---|---|---|---|---|---|---|---|---|
18" | 1158 | 1114 | 1510 | 1407 | 1342 | 1181 | 1212 | 1250 | 1366 | 903 |
17" | 1116 | 1060 | 1502 | 1396 | 1304 | 1178 | 1206 | 1227 | 1376 | 903 |
16" | 1130 | 1094 | 1489 | 1398 | 1306 | 1185 | 1207 | 1251 | 1340 | 900 |
15" | 1133 | 1083 | 1496 | 1369 | 1305 | 1178 | 1211 | 1241 | 1336 | 879 |
14" | 1096 | 1103 | 1483 | 1334 | 1294 | 1163 | 1224 | 1222 | 1349 | 883 |
13" | 1098 | 1071 | 1496 | 1381 | 1296 | 1147 | 1183 | 1248 | 1341 | 891 |
12" | 1089 | 1074 | 1476 | 1334 | 1293 | 1167 | 1221 | 1235 | 1335 | 892 |
11" | 1092 | 1079 | 1463 | 1360 | 1280 | 1180 | 1210 | 1223 | 1338 | 881 |
10" | 1115 | 1065 | 1452 | 1304 | 1270 | 1150 | 1169 | 1193 | 1316 | 859 |
9" | 1092 | 1042 | 1430 | 1315 | 1267 | 1129 | 1169 | 1203 | 1275 | 868 |
8" | 1092 | 1048 | 1396 | 1271 | 1212 | 1101 | 1158 | 1191 | 1268 | 857 |
7" | 1060 | 1056 | 1367 | 1284 | 1229 | 1073 | 1139 | 1162 | 1244 | 820 |
6" | 1049 | 993 | 1321 | 1249 | 1165 | 1063 | 1101 | 1133 | 1093 | 824 |
5" | 1029 | 1014 | 1286 | 1214 | 1156 | 1009 | 1097 | 1070 | 1172 | 796 |
4" | 956 | 948 | 1191 | 1113 | 1104 | 984 | 1014 | 1043 | 1120 | 762 |
3" | 907 | 893 | 1129 | 1045 | 998 | 890 | 948 | 965 | 1026 | 726 |
2" | 861 | 860 | 974 | 945 | 875 | 846 | 856 | 862 | 882 | 663 |
9mm Luger
Also known as 9mm Parabellum, 9x19mm, etc. Data is from Ballistics by the Inch.
Barrel Length | Cor-Bon 90 gr JHP +P | Cor-Bon 115 gr JHP +P | Cor-Bon 125 gr JHP +P | Cor-Bon 115 gr DPX | Federal 115 gr JHP text | Federal 135 gr Hydra-Shok JHP (low recoil) | Federal 105 gr Expand'g FMJ | Federal 124 gr Hydra-Shok JHP | Federal 147 gr Hydra-Shok JHP | Speer 124 gr Gold Dot Short Barrel |
---|---|---|---|---|---|---|---|---|---|---|
18" | 1754 | 1543 | 1449 | 1458 | 1297 | 1194 | 1370 | 1231 | 1038 | 1395 |
17" | 1766 | 1550 | 1421 | 1455 | 1320 | 1207 | 1381 | 1250 | 1096 | 1400 |
16" | 1740 | 1525 | 1430 | 1476 | 1295 | 1185 | 1358 | 1243 | 1073 | 1379 |
15" | 1768 | 1536 | 1392 | 1416 | 1304 | 1194 | 1364 | 1244 | 1090 | 1375 |
14" | 1767 | 1532 | 1405 | 1440 | 1295 | 1182 | 1372 | 1241 | 1090 | 1390 |
13" | 1738 | 1517 | 1477 | 1427 | 1281 | 1183 | 1343 | 1237 | 1081 | 1378 |
12" | 1716 | 1514 | 1385 | 1380 | 1282 | 1184 | 1273 | 1225 | 1081 | 1361 |
11" | 1690 | 1496 | 1372 | 1391 | 1268 | 1166 | 1318 | 1212 | 1059 | 1360 |
10" | 1647 | 1474 | 1372 | 1379 | 1253 | 1167 | 1314 | 1211 | 1067 | 1338 |
9" | 1663 | 1476 | 1369 | 1377 | 1238 | 1161 | 1307 | 1212 | 1055 | 1345 |
8" | 1634 | 1458 | 1366 | 1366 | 1234 | 1145 | 1278 | 1180 | 1047 | 1329 |
7" | 1619 | 1446 | 1329 | 1350 | 1223 | 1136 | 1258 | 1161 | 1040 | 1316 |
6" | 1566 | 1402 | 1312 | 1332 | 1188 | 1113 | 1235 | 1131 | 1030 | 1284 |
5" | 1539 | 1372 | 1282 | 1315 | 1166 | 1085 | 1194 | 1115 | 1007 | 1259 |
4" | 1444 | 1316 | 1226 | 1265 | 1094 | 1039 | 1140 | 1061 | 951 | 1203 |
3" | 1345 | 1245 | 1170 | 1215 | 1029 | 976 | 1074 | 988 | 902 | 1108 |
2" | 1215 | 1134 | 1061 | 1132 | 948 | 909 | 985 | 900 | 837 | 1074 |
Optimal Barrel Length For 9mm?
Based on the data above, it appears that almost all loads tested got their greatest percentage increase in velocity up until about a 7" barrel length. Velocity did of course increase further with longer barrels, but to a much smaller degree. For example, going from a 4" barrel to 7" (a 3 inch difference), every load got well over a 100 fps increase in velocity. However, going a full 10 inches longer up to a 17" barrel gained most of the tested loads under 100 feet per second in velocity. In fact, going from a 17 inch barrel up to 18 inches, actually LOST velocity in all but two of the loads, although the decrease was negligible.
It appears that overall, the optimal barrel length for something like an AR-15 pistol build, SBR, or similar setup, is about 7 to 8 inches for maximum efficiency and handling. If you still wanted to maintain an ultra-short setup with a suppressor, you could go even shorter with barrel length, as the additional length of the suppressor will increase velocity. Even at 7-8" barrel, the additional length of a suppressor would still allow the pistol or SBR to remain more compact than a 16" barrel. A 7" barrel with a 7" suppressor would still give an overall length of 14 inches. If you were looking for a rifle setup, there appears to be no major reason to go above the federal 16" barrel requirement, unless local laws differ, or whatever the case may be.
.460 Rowland
The .460 Rowland data below is sourced from Ballistics by the Inch.
Barrel Length | Cor-Bon Hunter 230 gr. JHP | 18" | 1356 |
---|---|---|---|
17" | 1366 | ||
16" | 1354 | ||
15" | 1352 | ||
14" | 1342 | ||
13" | 1344 | ||
12" | 1314 | ||
11" | 1293 | ||
10" | 1335 | ||
9" | 1303 | ||
8" | 1299 | ||
7" | 1273 | ||
6" | 1261 | ||
5" | 1208 | ||
4" | 1124 | ||
3" | 1082 | ||
2" | 974 |