Why is the 32 auto semi rimmed?

[lbmii]

What reason is there for the 32 auto to be semi-rimmed? Is it so it can be fired in revlovers chambered for other 32 caliber rounds? When 32 caliber revolvers were common, did people load them with 32 auto rounds? Would a 32S&W long revlover be safe to fire 32 auto rounds from it?

What other reason would the 32 auto have the semi rimmed design for?

 

[Crosshair]

Just my $.02

Quality control wasn't like it is now and the "headspace on the case mouth" was still a new thing at the time for straight walled cases. Cartridge case length and crimping methods might make the round headspace unreliably and cause misfires. Since these guns where meant mostly for defence, reliability was important. With the round being semi-rimmed it could still provide good headspace and still feed better than rimmed rounds.

 

[Onmilo]

John Browning designed the .32 automatic cartridge and the .38 automatic cartridge with the help of a man named John Petersen.

The idea at that time was that a semi-rimmed cartridge would allow for more reliable extraction from the semi automatic pistol designs of Mr. Browning.

The .32 Automatic was based on the .32 Short Colt cartridge and the .38 Automatic cartridges was based on the .38 Long Colt inside lubricated bullet cartridge.

While the designs worked brilliantly it was learned that a true rimless cartridge could be made to function just as reliably and the .45 Autoomatic cartridge followed suit here while Mssr. Borchardt and Mssr. Luger perfected the 7.63 mm and (mm cartridges in Europe.

The .32 Automatic and the .38 Automatic were never redesigned to be true rimless cartridges because hundreds of thousands of guns were produced in a relatively short period of time and nobody wanted to tick the owners of those guns off by redesigning a new, non-useable, version of what had become two old favorites.
Besides, if something works well already, why screw it up by redesigning it??

 

[max popenker]

Most common opinion is that these cartridges were originally intended for BOTH semi-autos and revolvers. Actually, great many smaller revolvers were built in Europe (especialy in Belgium) early in 20th century, chambered for Browning's cartridges like .25ACP and .32ACP (know as 6.35x16SR and 7.65x17SR in Europe, respectively)
OTOH, the .38ACP and .38Super never really caught up in Europe.

 

[Jim K]

The simple reason is that Browning didn't know any better. And Pedersen had nothing to do with it.

Browning began his auto pistol experiments with standard revolver cartridges, but soon found (surprise!) that they didn't work very well through a magazine. So he began to try to see how small he could make the rim to function reliably while at the same time giving adequate case support in the chamber. The "semi-rimmed" case was the best answer he could come up with.

But in May, 1904, a fellow named Georg Luger showed up in New York with some pistols that used a true rimless cartridge, supported on the case mouth. Whether Browning met Luger is doubtful, but it is probably not a coincidence that the cartridges Browning designed after that were rimless and supported on the case mouth.

Jim