Dumb Ammo Question: Rimless vs. ACP

ker2222

I know this is going to sound dumb, but I am new to collecting older weapons--just recieved my C&R a few weeks ago.

Anyway, is there any difference between "rimless" ammo and ACP ammo of the same caliber--like on the 1903 colts that take "32 rimless."

rufe-snow

" ACP " means Automatic Colt Pistol, this was just a marketing name that Colt used on their ammo to try to differentiate it from other manufacturers ammo.

.32 ACP ammo is the same as .32 Automatic & 7.65 x 17mm ( Metric Designation ), it's one of the most common handgun cartridges used. It's been in continuous use since 1900.

With certain few exceptions all of the above type ammo is interchangeable, no-mather what the manufacturer markings are.

Iconoclast

rufe-snow's answer is, as always, spot-on. However, I would point out an exception to the rule which illustrates why "ACP" <> "rimless" . . . this is the .38 ACP / .38 Super ACP . . . these are actually a semi-rimless case design which headspaces on the rim which is *very slightly* larger than the body of the case. A good beginning reference for ammunition which should serve to provide all the data you would ever need for issues such as this is Cartridges of the World. There are some minor technical errors in this publication which have accumulated over the years (apparently they do not make corrections, or all of them, between editions), but for the individual who is not specializing in ammo collecting, it is more than adequate.

"There is nothing lower than the human race - except the French." (Mark Twain) ". . . And DemoCraps" (me)

v35

The 32 auto and 25 auto are also semi rimmed and not rimless as is the 45ACP. There's enough of a rim to enable shooting in a revolver, although not always the smartest idea.
As a 12 year old I fired 38 Super Auto cartridges out of an old Thames top break 38 S&W revolver. After about one or two shots, the barrel catch blew off and the cylinder flew over my head. I wired it closed and got a few more shots before it was confiscated.
Interestingly, the cylinder never burst.

jsergovic

The older rounds may be black powder rounds, so if you are shooting as well as collecting, ask around first.

I almost blew my head off with modern .41 magnum rounds in a revolver made for .41 mag black powder loads.

1KYDSTR

While not sure I think you might be referring also to the 45 ACP vs. 45 Auto rim differentiation. The 45 Auto Rim was a cartridge that was put into use after WWI to use in Colt and S&W revolvers that were issued during the war that used the 45 ACP round as there were not enough 1911 autos produced at the onset of U.S. involvement in the "Big War". These guns (the revolvers) used "Moon clips" that held the rimless 45 ACP in place in the cylinder...otherwise the firing pin could not always strike the primer and extracion of the spent cartridges was a real pain in the but! The Auto Rim was identical to the 45 ACP except it had a rim on ot so it could head space and extract normally. This cartridge variation was put in place for the civilian market to make those old revolvers functional for everyday use. I just went back and looked at your original post and realized this wasn't the answere you sought...sorry..hope it was still interesting enough to read though! All I can say is heed the advicwe given earlier and buy a copy of Cartridges of the World...a very useful guide to the novice and seasoned collector alike!

"When I cease learning...I'm dead"(Me)
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