The .32 ACP Cartridge

The 7.65mm Browning cartridge (later known as the .32 ACP) was first introduced not to the U.S., but to the European market in 1899 by the Belgium firm Fabrique Nationale in John M. Browning's first successful semiautomatic pistol, the Model 1900.   The invention of this cartridge was responsible, more than any other factor, for the introduction and worldwide distribution of the cheap pocket auto pistol.

The Browning M 1900 (left) and the Colt 1903 Pocket Model (right)

Colt - after rejecting Browning's initial offer of the Model 1900 (Browning took it to Colt before bringing it to Europe) - introduced its first Browning-designed autoloader, the Pocket Model in 1903.   The 1903 Pocket Model was chambered for the same cartridge, but Colt renamed it the .32 Automatic Colt Pistol, or .32 ACP for short.

The cartridge was introduced with a 71 grain full metal jacket bullet at a muzzle velocity of slightly over 900 fps for around 130 foot pounds of kinetic energy.   It was designed for early blowback semi-automatic pistols which lacked a barrel locking mechanism; the relatively low power of the .32 ACP round made it a practical blowback round.

Many companies offer factory loads for this cartridge.   For self defense, many people recommend Winchester's Silvertip with a 60 grain hollowpoint bullet at 970 fps.   Winchester lists the muzzle energy of its factory load as 125 foot pounds.   However, I'm convinced that the only thing even close to an adequate self defense load would be either the S&B, or one of the hotter European loads with a FMJ bullet.   You're better off hoping for decent penetration rather than trying to make a big hole at the expense of penetration.

The .32 ACP is a semi-rimmed round - the rim has a diameter about 0.020" larger than the case.   To prevent rimlock, handloaders should take care to load the cartridge as close to the maximum overall length (OAL) of 0.9840" as possible.   Rimlock is a condition that occurs in the magazine when the rim of the top round gets behind the rim of the round just below it.   When the gun fires, the slide is unable to strip the top round off the magazine and the gun fails to feed.   Racking the slide doesn't help to clear the condition; you must remove the magazine and insert a new one.

Normal stacking (left).   Rimlock occurs when the top round jumps over the rim of the round below it (right).

Rimlock should not occur if the rounds are properly sized to the magazine.   In other words, make sure the rounds are long enough so that there's not enough room in the magazine to allow the top round to jump over the rim of the round below it.   Rimlock occurs more frequently with hollow point ammo as these rounds tend to have a shorter OAL than FMJ ammo.   To prevent rimlock on shorter rounds, you can add a spacer inside the back of the magazine to take up the extra room.  

Though many other cartridges enjoy far greater publicity, it is thought that more handguns have been chambered for the .32 ACP cartridge than for any other. During the first 10 years of the .32 ACP's existence, FN alone produced over 500,000 pistols in this caliber.   Even though this cartridge is weak, 80% of the automatic pistols made before WWII were chambered for it - mainly because the cartridge is so weak.   It's low chamber pressure renders it safe to use in light, cheaply-made blowback actions. Practically every manufacturer of autoloading handguns has at one time or another built small pocket autoloaders in .32 ACP with famous names like Savage, Walther, Mauser, Colt, Remington, and FN/Browning on the list.   Manufacturers including Beratta, Seecamp, Kel-Tec, and North American Arms continue to manufacture pocket guns in .32 ACP.

The groove diameters of barrels in this caliber can vary from .308 inch to .313 inch among the various manufacturers.

The .32 ACP is a cartridge with many names.   Among them:

  • 32 Auto (typical designation in America)
  • 32 ACP (Automatic Colt Pistol)
  • .32 Browning Auto
  • 7.65 x 17mm
  • 7.65 x 17mmSR (SR designating Semi-Rimmed)
  • 7.65 mm Browning (typical designation in Europe)

Ballistic Data

The table below shows the chronograph results of 2 strings of 10 shots each with three different brands of ammo.   When I get a set of dies, I'll post some handload data as well.

Test Firearm: Savage Model 1907 (of course)

Round Avg. Velocity Fastest SlowestStd. Deviation
Sellier & Bellot 73 gr FMJ 932 936 90017
939 957 91312
Remington 71 gr FMJ 935 972 91320
934 972 90118
Winchester 71 gr FMJ FP 809 840 75923
817 834 78713

Load Data

The load data below comes from the Speer No. 13 Reloading manual.   All loads shown below are marked DNR (Do Not Reduce).

BulletSpeer .312" dia 60gr Gold Dot HP (Speer Part# 3986)
Powder Weight (grs) Muzzle Velocity
Power Pistol3.61030
Red Dot2.31030
H. Universal3.01021
Win. 2312.81007
AA #2 Improved2.6963