The 32 ACP Revisited
I've reloaded for the .32 ACP for over thirty years. These pocket guns don't have any great reputation for accuracy. The Speer No. 13 handbook states that 3-4" groups at 25 yards are the best you can hope for. This agrees with my experience. WWII German military and postwar German police acceptance accuracy standards which allowed 5 mils or 75mm of dispersion (about 3") at 15 meters (approximately 49 ft.). My Beretta Model 3031 Tomcat barely does this with good ammo when I do everything right. Typical 25-yard eight-shot groups are more like six inches. More traditional Full-sized .32 pocket pistols do much better and are more useful as field guns for small game within 50 feet or so.
Any pocket pistol which groups better than 4 mils, or 60mm (2.36") at 15 meters is said by Europeans to be quite good. My experience with a dozen .32 ACP pistols over the years suggests the most accurate pocket pistols are the Walther PP (not the PPK - it little better than the mouseguns), FN M1922, Mauser HSc, Beretta M70, Colt Pocket and CZ27. Any of these reliably group about 2-1/2” at 50 feet, with good ammo. The best .32 Automatics using tweaked handloads can do about 2 inches at 50 feet over a series of groups without excluding any "called shots" or fliers, but accepting all the data as it comes. Any pocket pistol which does so should be considered a “keeper.” This is reality.
Testing, WWII-era .32 autos in my collection, typical results are 4 inch group averages in series of five consecutive 8-shot groups at 25 yards, firing full magazines off sandbags with European CIP specification RWS, Privi Partisan, Sellier & Bellot or Fioccho Ball ammo. This compares to what typical 2-inch .38 Special snubbies do for five or six shots off sandbags at the same range with +P service ammo, a good benchmark. The limiting factor in accuracy of small handguns is short sight radius.
A personal defense gun will most likely to be used from near-contact distance to no more than 10 meters. Sight radius is less important because the recommended technique in close quarter defense situations is "target focused" maintaining situational awareness, watching the bad guy's hands, moving to cover, etc., rather than being "sight focused," as it tends to be when engaging targets beyond ten meters, such as the grouse or rabbit you want to eat.
My favorite cast bullet handloads in .32 ACP use either the 98-grain Saeco #325 semi-wadcutter, Meister 94-gr. .312 flatnose or the 88-gr. NEI #82 flatnose. If you do not cast your own bullets, just buy the Meisters, load 1.7 grains of Bullseye and seat bullets to 0.95-0.97" overall cartridge length. If you cast your own, use wheelweights, tumble-lubricate the as-cast bullets with Lee Liquid Alox, and load them as-cast and unsized with 1.7 to 1.8 grain of Bullseye. The Saeco #325 bullet can be crimped in the normal revolver crimp groove. Do not load the NEI or Meister bullets shorter than 0.95 inch. I taper crimp using a custom Lee Factory Crimp Die which has a carbide full length sizer. This removes any bulges caused by mis-match of bullet diameter with case wall taper, profiles the loaded rounds for easy chambering and sizes the bullet, if needed by compression inside the case. A custom Lee Factory Crimp Die (FCD) costs $30. I highly recommend one for anyone who is serious about reloading for the .32 ACP.
Using the 88-grain NEI #82 bullets 2 grains of Bullseye is a full charge load which should not be exceeded. Do not exceed 1.8 grains of Bullseye with cast bullets over 90 grains.
A lot of misunderstanding is caused by inaccurate mythology and folklore in old Lyman manuals which recommends sizing cast bullets to the groove diameter of the barrel. This results in undersized bullets not fitting the forcing cone or throat and being gas-cut, causing leading at the origin of rifling and poor grouping.
The recommended practice for lead bullet ammunition in the firearms industry is that lead bullets be of a diameter to enter the throat or forcing cone without resistance, but to fit as closely as possible so that the bullet upsets to form a positive gas seal instantly upon discharge. The ideal condition is for bullet alloy hardness to be matched to working chamber pressure, and for the bullet to be not smaller than 0.0005 under throat size.
Typical wartime European pistols vary all over the map with respect to barrel bore and groove dimensions, twist rate and chamber dimensions. Colts, Berettas and Walthers have 16 inch twist, FNs, CZs and Mausers have 10 inch twists.
FN, Mauser and Walther pistols in my collection typically have groove diameters of .307-.309, Berettas, CZs and Colts run .310-.312. I have not seen chamber throats smaller than .311, but have seen WWI and WWII era Spanish, French and Italian pistols as with throats as large as .316. This wide variation in bore sizes coupled with factory jacketed bullet diameters from .308 to .312 explains a lot of the accuracy problems people experience with the .32 ACP.
In my experience European Sellier & Bellot, Sako, Lapua, and RWS ammo having the smaller bullet diameter works best in Walthers, Mausers, MABs and FNs, while larger Privi-Partisan, Fiocchi and handload using Magtech, Remington Hornady and Speer jacketed bullets are more accurate in Kel Tec, Beretta, Colt, Astra, Unique, Star, Llama and CZ.
My 1935 Beretta wartime pistol had an oversized .315 throat with .313 groove diameter barrel and produced six inch-plus groups at 25 yards with its original WWII salt and pepper barrel. After fitting a new barrel machined from a 14 inch twist Hart .308 blank with minimum CIP chamber and .312 throat set up to headspace on the case mouth groups shrunk to 3 inches at 25 yards with good ammo, using iron sights.
I had two custom barrels made to fit a Beretta European target pistol chambered in .32 ACP, of nominal .300 bore and 308 groove dimensions, with 10 inch and 14 inch twist barrels, respectively, chambered with the same reamer. Firing off sandbags with a 4X Leupold scope the target pistol would shoot an inch at 25 yards with the best hardball ammo, and 1-1/2 inches with my cast bullet handloads. Don't ask what it costs to machine a chunk of Hart barrel and have custom chambering reamers and headspaces gages ground. If you need to ask, you cannot afford it. Figure seven hours of machine time, plus the cost of barrel blanks and tooling. Ahh...what we do for science~!
European CIP throat dimensions specify 7.9 + .05mm - 0.0 mm. or .311-.313", so for most pistols a .313 bullet is correct, but some wartime pistols may need .314 bullets, if they will chamber safely without resistance. If your chamber is tight, but the throat is large, good results can be obtained by loading the bullet as-cast and unsized, leaving a portion of the driving shoulder exposed ahead of the case mouth to fill the throat, and using a custom Lee Factory Crimp die to profile the loaded rounds to within max. cartridge dimensions, eliminating any case bulges caused by mis-match of bullet diameter to internal case wall taper.
A good approximation of proper alloy hardness is estimated using the rule 3(BHN)x480 = working pressure.
US .32 ACP ammunition is loaded to a maximum product average of 16,000 psi. Solving for BHN we get: 3(480) / 16,000 = 11 BHN, which works well for mild loads which are at the minimum for reliable functioning.
European ammunition loaded under CIP may reach 20,500 psi. My wartime Beretta, FN and CZ pistols steadfastly refuse to function with anemic US ammo, so hotter loads needed to function reliably require harder alloy:
3(480) / 20,500 = 14 BHN
I load 88-98 gr. cast bullets in the .32 ACP all the time. The store-bought solution is the Meister 94-gr. flatnosed .312 diameter bulk bullets with 1.7 to 1.8 grains of Alliant Bullseye, the charge varied depending upon case weight. RWS and Fiocchi brass weigh 40 +/- 1 grain and get the lighter charge. Remington brass weighs 36 +/- grains and gets the heavier charge. Either load gives about 750 f.p.s. in a 10cm barrel such as the Walther PP or FN M1922 Browning. In guns which feeds SWCs, I use the 98-gr. Saeco #325 with 1.7 grains of Bullseye, and crimp in the normal revolver crimp groove. Its large flat nose is very effective on small game.
Do not shoot a lot of heavy bullet loads in .32 ACPs having light aluminum alloy frames, because they are harder on the gun. They work best in steel-framed European guns which are balanced for heavier bullet 73-74-gr. ammo. My WWII-era pistols don't function at all well with typical US 71-gr. commercial ammo or 60-gr, JHPs.
In my chronograph testing Remington, Winchester, Federal and Magtech 71-gr. FMJ ammo average only about 850 f.p.s. from a full sized pistol such as the Walther PP, Beretta M70 or FN M1922. CIP specification 73-gr. ammo such as RWS, Geco, Fiocchi or Sellier & Bellot goes 900-950 f.p.s. American 60-gr. JHPs typically give about 900 f.p.s. but because of their light bullet, may not have enough recoil impulse to reliably operate older European pistols.