JOHN TAFFIN
The modern beginnings of the 10MM go back to the early 1970’s with the creation of the .40 G&A. At the time, there were three semi-auto cartridges of any serious consequences available, the 9MM, the .38 Super, and the .45 ACP. The idea was to come up with a cartridge that combined the best qualities of the 9MM and .45 ACP. With the creation of the new .40 semi-auto cartridge, the statement was made that “…the .40 caliber was chosen because it can be shown mathematically that it takes about this size projectile to provide the cross-sectional area to achieve adequate stopping power at reasonable pistol velocities.”
There are any number of experts, men who have first hand knowledge of bullet performance in both hunting and defensive situations, who would dispute that there is any such thing as stopping power. Penetration combined with hitting vital areas seem to be much more important and the .40 G&A would certainly offer excellent penetration capabilities by combining the speed of the 9MM with the bullet weight of the .45 ACP. The larger the caliber, the better the chance of hitting vital areas. The .40, while not as good as the .45 in this respect, is certainly better than the 9mm, speaking strictly from the standpoint of the cross sectional area offered by each cartridge.
The .40 G&A was wildcatted using cut down .224 Weatherby brass and 180 grain .38-40 bullets. Chambered in a Browning Hi-Power, maximum velocities were right at 1250 feet per second. The .40 G&A went nowhere but it opened the doors for the 10MM.
Now enters the Bren Ten. In 1984, Jeff Cooper put his stamp of approval on a new semi-automatic from Dornaus & Dixon, the offspring combining some of the best features of the Czech made CZ-75 9mm with the distinct advantage of a larger hole in the barrel. The amazing thing is that Chairman Jeff took to heart a semi-auto that was not chambered in .45 ACP and was a double action semi-automatic. The new caliber was the 10mm, and the new semi-auto, while a double action, could be carried cocked-and-locked.
Cooper named the new handgun the Bren Ten, BR for the BRNO factory in Czechoslovakia and EN for the British Enfield factory. Bren Ten made a catchy name for the new 10mm. Unfortunately, the name still exists and the Bren Ten itself is no more. By 1987, Dornaus & Dixon had gone into bankruptcy.
The gun died, but the cartridge did not. Colt rescued it by chambering the Government Model, renamed the Delta Elite, and 10mm handguns have been available from Springfield Armory, IAI, LAR, Thompson/Center, Glock, Smith & Wesson with the 1006 and 1016. I can think of no other instance in history whereby the original handgun died so quickly, and yet the cartridge lived on in so many persuasions most of which are now also gone.
Loading the 10mm proved to be sufficiently easy with the use of RCBS Carbide dies. I always like to leave about one-sixteenth of an inch of the shoulder of any semi-auto bullet exposed. This works with some bullets in the Colt 10mm but loads for the Javelina must be seated with the shoulder flush with the case mouth.
Four jacketed bullets were shot extensively in the Colt and Javelina 10mms. Those bullets were Sierra’s 150 and 180 grain jacketed hollow cavities, Speer’s 190 FMJ, and Hornady’s 200 grain FMJ. A fifth jacketed bullet, Hornady’s 170 grain jacketed hollow point was used in the Javelina alone.
The 10mm proves to be quite fussy about the jacketed bullets and load combinations it is being fed. The Speer 190 would not group at all with either of the Colts with any of the loads tried. Switching to the Javelina, the same Speer 190 would shoot into less than two inches with the right load. I called Speer and they related that they too had had problems in the Colt Delta Elite and others have related that the Delta Elite is no great shakes accuracy-wise with any loads tried. Both Colt Delta Elites I used for testing the 10mm had been worked over with slide tightening, trigger jobs, etc, but had stock barrels.
Many jacketed loads proved to be exceptionally accurate in the Colt Delta Elites and the Javelina with many loads grouping under two inches or less at 25 yards when fired using the Outer’s Pistol Perch as a rest. A sandbag is placed in the barrel notch of the perch and another is placed on the platform that serves as a hand rest. This proved to be the best way of using the Pistol Perch for accuracy testing.
Some excellent loads surfaced as the testing progressed. With jacketed bullets in the 180 to 200 grain category, 10.5 grains of AA#7 gave velocities in the 1100+ fps range and consistently grouped in two inches or less with both the Delta Elites and the Javelina. This same load gave the same excellent results with the RCBS #10mm-200 cast bullet in the Colt Delta Elites. Groups ran in the one and one-half inch range with velocities at 1200 feet per second. Switching to the Javelina, 11.0 grains of AA#7 gives 1281 feet per second and groups right at one-inch. An excellent practice or competition load for the 10mm with the RCBS cast bullet proved to be 5.5 grains of WW231. This load goes 1000 fps from the five-inch barrel of the Delta Elite and 1075 fps from the seven-inch barrel of the Javelina. Accuracy is so good, I would search no more. This load makes major with plenty to spare, is easy to handle and consistently groups under one and one-half inches. For a lighter cast bullet, I use the Bull-X 175 grain semi-wadcutter. The same 5.5 grains of WW231 gives velocities of 1050 in the Delta Elites and 1100 in the Javelina. Easy shooting and easily makes major for action shooting competition.
Is the 10mm a hunting pistol? With qualifications, yes it is . The qualifications are the proper ammunition and especially discretion. Pushed to the limit, the 10mm is better than the .357 Magnum but still quite a bit below the .41 Magnum. I have been using the 170 Hornady Jacketed Hollow Point and have developed a warm load of 13.0 grains of AA#7 for 1374 feet per second from the seven-inch Javelina. This should do the job on small deer without any problem. This load should also be worked up to carefully starting at around 11.0 grains.
LOADS FOR THE 10MM
FIREARM: COLT DELTA ELITE BARREL LENGTH: 5″
BRASS: MIDWAY 10MM PRIMER: WINCHESTER WSP
CHRONOGRAPH: OEHLER MODEL 35P GROUPS: 5 SHOTS @ 25 YARDS
JACKETED BULLETS
BULLET LOAD MV GROUP
SIERRA 150 JHP 11.5 GR. AA#7 1212 3 1/4″
12.0 GR. AA#7 1267 2 3/4″
12.5 GR. AA#7 1315 3″
8.5 GR. AA#5 1097 2 5/8″
9.0 GR. AA#5 1163 1 5/8″
9.5 GR. AA#5 1251 2 3/4″
10.0 GR. AA#5 1296 3 1/2″
10.5 GR. AA#5 1324 1 7/8″
7.5 GR. HERCO 1186 2 1/4″
8.0 GR. HERCO 1199 2″
8.5 GR. HERCO 1218 2 3/4″
9.0 GR. HERCO 1296 3″
SIERRA 180 JHP 10.0 GR. AA#7 1073 2″
10.5 GR. AA#7 1139 1 1/2″
11.0 GR. AA#7 1182 2 1/4″
7.5 GR. AA#5 992 2 7/8″
8.0 GR. AA#5 1045 3″
8.5 GR. AA#5 1112 3 1/8″
9.0 GR. AA#5 1179 1 1/2″
10.0 GR. HS-7 1140 2 3/8″
10.5 GR. HS-7 1202 2 5/8″
11.5 GR. HS-7 1292 2 1/8″
10.0 GR. WW540 1196 3″
10.5 GR. WW540 1255 1 7/8″
7.0 GR. HS-6 876 2 1/8″
7.5 GR. HS-6 948 4 1/2″
8.0 GR. HS-6 1062 2 1/2″
5.0 GR. WW231 889 4″
5.5 GR. WW231 971 3″
6.0 GR. WW231 1047 2 7/8″
HORNADY 200 FMJ 10.0 GR. AA#7 1088 3″
10.5 GR. AA#7 1138 1 5/8″
11.0 GR. AA#7 1167 3″
7.5 GR. AA#5 990 2″
8.0 GR. AA#5 1057 2 1/2″
8.5 GR. AA#5 1099 4 3/4″
9.0 GR. HS-7 1034 2 1/2″
9.5 GR. HS-7 1122 1 3/4″
10.0 GR. HS-7 1141 2″
9.0 GR. WW540 1051 2″
9.5 GR. WW540 1139 2 7/8″
6.5 GR. HS-6 842 3″
7.0 GR. HS-6 892 4 3/4″
7.5 GR. HS-6 946 3″
4.5 GR. WW231 805 2 1/4″
5.0 GR. WW231 895 3″
5.5 GR. WW231 952 3 1/2″
CAST BULLETS
BULLET LOAD MV GROUP
RCBS #10MM-200 9.0 GR. AA#7 1022 2″
10.0 GR. AA#7 1130 1 3/4″
10.5 GR. AA#7 1204 1 1/2″
5.0 GR. AA#5 742 2 1/8″
6.0 GR. AA#5 893 2″
7.0 GR. AA#5 983 2 1/8″
8.0 GR. HS-7 945 2″
9.0 GR. HS-7 1123 1 3/4″
5.0 GR. WW231 950 1 1/4″
5.5 GR. WW231 1010 1 3/8″
6.0 GR. WW231 1083 2 1/2″
8.0 GR. BLUE DOT 1005 2 1/8″
9.0 GR. BLUE DOT 1091 2 1/4″
10.0 GR. AA#9 919 3 1/4″
11.0 GR. AA#9 1039 3 1/2″
12.0 GR. AA#9 1108 2 1/8″
BULL-X 175 SWC 8.0 GR. AA#7 936 3 3/8″
9.0 GR. AA#7 986 2″
10.0 GR. AA#7 1142 3 1/2″
11.0 GR. AA#7 1213 2″
12.0 GR. AA#7 1328 2 5/8″
9.0 GR. BLUE DOT 1116 3 3/4″
10.0 GR. BLUE DOT 1206 3″
4.5 GR. WW231 846 2 3/4″
5.0 GR. WW231 965 2 1/8″
5.5 GR. WW231 1047 2 1/2″
6.5 GR. AA#5 923 3 3/8″
7.0 GR. AA#5 966 3 1/2″
7.5 GR. AA#5 1050 2 5/8″
FACTORY LOADS
BULLET LOAD MV GROUP
150 GR. JHP HORNADY 1278 1 7/8″
200 GR. FMJ HORNADY 1113 2 3/8″
170 GR. JHP PMC 1150 2 1/4″
200 GR. FMJ PMC 1067 2 1/4″
170 GR. SWC LOAD-X 1050 1 3/8″
FIREARM:AMT JAVELINA 10MM BARREL LENGTH: 7″
BRASS: MIDWAY 10MM PRIMER: CCI #300
CHRONOGRAPH: OEHLER MODEL 35P GROUPS: FIVE SHOTS AT 25 YDS.
BULLET LOAD MV GROUP
SIERRA 150 JHP 13.0 GR. AA#7 1406 2 1/4″
SIERRA 150 JHP 12.0 GR. BLUE DOT 1463 2 1/2″
HORNADY 170 JHP 13.0 GR. AA#7 1374 2″
HORNADY 170 JHP 11.0 GR. BLUE DOT 1323 2 1/2″
SIERRA 180 JHP 10.5 GR. AA#7 1164 1 3/4″
SIERRA 180 JHP 12.0 GR. AA#7 1274 2 3/8″
SIERRA 180 JHP 10.0 GR. BLUE DOT 1225 2 3/8″
SIERRA 180 JHP 5.5 GR. WW231 959 1 7/8″
SPEER 190 JFP 10.5 GR. AA#7 1162 2 1/4″
SPEER 190 JFP 11.0 GR. AA#7 1189 4 1/4″
SPEER 190 JFP 10.0 GR. BLUE DOT 1212 5 1/2″
SPEER 190 JFP 5.5 GR. WW231 934 1 3/4″
HORNADY 200 JFP 10.5 GR. AA#7 1171 2 1/4″
HORNADY 200 JFP 11.0 GR. AA#7 1179 1 1/2″
HORNADY 200 JFP 9.0 GR. BLUE DOT 1132 3″
HORNADY 200 JFP 5.5 GR. WW231 948 1 3/4″
CAST BULLETS
RCBS #10MM-200 10.5 GR. AA#7 1229 2 3/4″
RCBS #10MM-200 11.0 GR. AA#7 1281 1 1/4″
RCBS #10MM-200 10.0 GR. BLUE DOT 1321 3″
RCBS #10MM-200 5.5 GR. WW231 1078 1 1/2″
BULL-X 175 GR. SWC 5.5 GR. WW231 1096 1 3/4″