9mm Largo Loading Data
WARNING
The information on this page was transcribed by me. I have checked the information 3 times against the original, but make no guarantees to it's accuracy. Use these loads at your own risk. I take no responsibility for the condition of your firearms, reloading knowledge, or results. Please do not start with maximum loads, reduce the load by 5% and work up from there.

Test Specifications
Firearm Used: Star Super
Bbl. Length/Twist: 5.150" 1x16"

Test Components
Cases: Starline
Trim-to Length: .900"
Primers: Win Small Pistol

Remarks:
Although virtually unheard of until recently, the 9mm Largo is not a new cartridge. Developed in the early 1900's as a military pistol cartridge, it was adopted by the Danish (Model 1910) and the Spanish (Star and Astra) military. Also known as a 9mm Bayard, Bermann, Bergmann-Bayard, Bayard Long, Danish and 9 x 23, the Largo is almost exactly like the popular 38 Super except being rimless and having a deeper extractor groove.

9mm Luger, 9x21, 9x23 and 38 Super dies will all work to load the Largo. The surplus ammo available is all berdan primed, but for the reloader, Starline Brass makes cases just for the 9mm Largo.

Due to the deeper extractor groove, 9mm shell plates and shell holders don't work well. In the Dillon, we found the #3 shell plate (.222, .223, etc.) with #3 buttons worked well on the Model 550.

One thing we noticed in the Star we tested and others we examined was the diameter of the firing pin hole being exceptionally large allowing the primer to flow back into the opening. We suggest using primers with hard cups such as Winchester or CCI to help prevent that.

.355 90 gr. JHP Cartridge OAL: 1.190"
Powder/Velocity1200125013001350140014501500
Bullseye5.15.45.76.06.36.66.9
WW2315.25.55.86.16.56.87.1
Power Pistol6.36.67.07.37.78.08.3
AA#57.57.98.28.69.0

Univ Clays5.86.06.26.46.66.87.0
HS-68.48.68.99.19.49.69.9
Viht 3N377.37.57.77.98.18.38.5
AA#79.29.610.010.410.811.1
Energy/ft. lbs.288312338364392420450
Accuracy Load: Viht 3N37/8.1 grs.; 1400fps/392 ft.lbs.
Hunting Load: Power Pistol/8.0 grs.; 1450 fps/420 ft.lbs.

.355 95 gr. FPJ Cartridge OAL: 1.200"
Powder/Velocity1150120012501300135014001450
Bullseye4.95.25.55.86.16.36.6
WW2315.25.55.86.16.46.77.0
Power Pistol6.46.77.07.37.67.98.1
AA#57.37.78.28.69.1

Univ Clays5.65.86.06.26.46.66.8
HS-68.18.38.68.89.19.39.6
Viht 3N376.97.17.37.67.88.08.3
AA#78.58.99.49.910.410.9
Energy/ft. lbs.279304330356384413443
Accuracy Load: Viht 3N37/8.0 grs.; 1400fps/413 ft.lbs.
Hunting Load: Bullseys/6.6 grs.; 1450 fps/443 ft.lbs.

.355 115 gr. JHP Cartridge OAL: 1.250"
Powder/Velocity1100115012001250130013501400
Bullseye4.95.25.55.86.0

WW2315.05.25.55.76.0

Power Pistol6.26.56.97.27.67.9
AA#56.97.37.78.18.58.9
Univ Clays5.05.35.65.96.26.5
HS-67.27.57.98.28.68.9
WAP6.56.87.17.78.08.3
Viht 3N376.26.56.87.17.57.8
AA#78.79.19.59.910.4

Energy/ft. lbs.309338368399431465501
Accuracy Load: Viht 3N37/7.5 grs.; 1300fps/431 ft.lbs.
Hunting Load: Univ Clays/6.5 grs.; 1350 fps/465 ft.lbs.

.355 125 gr. FMJ Cartridge OAL: 1.300"
Powder/Velocity1050110011501200125013001350
Bullseye4.54.85.25.55.9

WW2314.75.05.35.65.9

Power Pistol6.06.36.66.97.27.5
AA#56.87.17.57.88.28.6
Univ Clays5.15.45.76.06.26.5
HS-66.97.37.68.08.4

WAP5.45.86.26.77.17.68.0
Viht 3N376.16.46.77.07.37.5
AA#78.58.99.29.59.8

Energy/ft. lbs.306336367400434469506
Accuracy Load: Viht 3N37/7.3 grs.; 1250fps/434 ft.lbs.
Hunting Load: WAP/8.0 grs.; 1350 fps/469 ft.lbs.

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