32 AUTO DEFENSIVE AMMUNITION

The 32 Auto cartridge is a compromise choice for self-defense. Handguns that shoot this cartridge can be very small, like the Kel-Tec P32. This small size allows them to be concealed to where an experienced observer would be unable to tell that you have a gun. The price paid for this is poor terminal performance. Below is the data for several FMJ and JHP bullets shot into bare gelatin from a Kel-Tec P32.

Shots into bare gelatin give a bullet the best opportunity to expand. JHP bullet expansion was good, with exception of the Hornady XTP. All bullets that expanded had 95% or greater weight retention which demonstrates good bullet design. Bare gelatin is where you start testing bullets of marginal expansion. More indicative of the ‘real world’ is what a bullet does after heavy clothing. Bullets retrieved from soft tissue in bodies closely resemble bullets pulled out of gelatin blocks covered with heavy clothing.

Lucky Gunner tested the above ammunition in Clear Ballistics blocks covered in FBI Heavy Clothing (t-shirt material, linen shirt, light fleece and one layer of denim layered together.) Clear Ballistics does not duplicate the penetration depth of bullets shot into 10% ballistic gelatin but it does duplicate expansion. When a bullet expands, it pushes a larger hole in tissue which promotes bleeding. The most combative opponent cannot physically continue their attack without sufficient blood flow, so bullet expansion is important.

The Hornady XTP 60gr failed to expand in bare gelatin so it can be expected to fail to expand in heavy clothing. The Cor-Bon JHP 60gr load failed to expand reliably after the heavy clothing. Federal Hydra-Shok 65gr JHP expanded 80% of the time in the Lucky Gunner tests after the heavy clothing.

The partial expansion of this bullet was just enough to expose the notching between jacket segments (circled in red above.) Exposed notching is good … the inconsistency and partial expansion are drawbacks. Notching like this cuts tissue as it presses into the ‘V’ between jacket segments, increasing bleeding.

32 Auto gives you the choice of unreliable expansion or reliable penetration. None of the tested hollowpoints are good from a pocket pistol but the Federal Hydra-Shok has the potential most of the time to increase damage done on a soft tissue shot. This Hydra-Shok averages 11 ft-lbf energy transferred from the bullet per inch of penetration. For comparison, an average 380 Auto 90gr JHP transfers 18 ft-lbf per inch of penetration.

Bone penetration is important considering how much bone is present when an attacker is turned to face you (about 80% of the target is covered by bone.) Bones protect vital organs and cause bullets not to expand. Whether or not a bullet can expand in soft tissue after bone or at the minimum can penetrate through bones at all must be considered when choosing ammunition for self-defense.

There is a well-established inability of pistol cartridges less energetic than 9mm Luger to penetrate an attackers skull. A well-known example being Special Agent McNeill’s 38 Special +P bullet failing to penetrate the temple of a suspect in the FBI Miami shootout. This bullet impacted the suspects temple with ~270 ft-lbf kinetic energy – a 32 Auto bullet has ~100 ft-lbf kinetic energy so cannot be considered capable of damaging tissue protected by the skull.

The best choice for 32 Auto defensive ammunition is a Full Metal Jacket semi-wadcutter FMJ like the one below at middle. It is referred to in the results as a ‘flat meplet.’ A JHP cartridge is pictured at left and a Full Metal Jacket round nose is at the right for comparison.

It is clear from the difference in terminal performance that 32 Auto expanding bullets were designed around the SAAMI length test barrel, which is 4.0″ long. Since 32 Auto is not in use by US law enforcement, there is very little monetary incentive for ammunition manufacturers to design any special use ammunition for this cartridge. While still a deadly instrument, a 32 Auto handgun should be considered among the best weapons of last resort.

Until next time… Stay Alert, Stay Alive.