An explanationof calibre please, 7.65 vs 32

Discussion in 'Technical Questions & Information' started by powdersmoke, Sep 1, 2004.

  1. powdersmoke

    powdersmoke New Member

    Oct 4, 2003
    Brooksville, FL
    Just got the CZ-70. I was told it was 32 acp. So I bought a box of twenty 32 cal. and shot 12 rounds through it. Being the idiot I am I just noticed on the slide 7.65 was stamped as calibre. What gives.

    A 7.65 cal. is .301 inches. How can I shoot a 32 cal acp through it? Is this a bad thing? Seems like 8mm would be closer to .32. What about a 9mm, can you shoot .357 through it or .38???

    I'm just the village idiot. Don't know anything about these newer firearms.
  2. The 7.65mm is .32 caliber. Many of the measurements used in firearms are the BORE size before rifling, after rifling the internal diameter of a barrel is enlarged. So it is the measurement between GROOVES that is .312", not the measurement between the LANDS. Confused? Yea, so are we! ;)

  3. Icon-oclast

    Icon-oclast New Member

    Aug 19, 2004
    Actually, the ".32" is at least as inaccurate as the "7.65" and while I don't know the history on the latter, perhaps I can help explain the former.

    You may have seen the story (spoof or historical analysis?) making the rounds roughly four years ago explaining why the size of the space shuttle body corresponds to width of the butts of Roman horses? A somewhat analagous situation pertains here.

    Many of our .32 & .38 caliber revolver rounds are descended from the early Colt .31 and .36 cap and ball revolvers. As S&W rimfire firearms came on the market, they paralleled those bore sizes, but S&W chose to create cartridge names which would differentiate the new high tech loadings from the earlier designs. And when the Colt firearms were converted to self-contained ammunition, obviously the bore size did not change. As newer versions designed for self-contained ammunition came on the market, the makers did not re-invent the wheel, but used the same ammunition and nomenclature. S&W did try to put the genie back in the bottle with the first offerings of the .38 S&W round - the first production firearms and ammunition were labeled .36/38 S&W. This didn't fly, so they reverted to the ".38" terminology. The mislabeling continued as we moved into the modern era and was carried over to the pistol cartridges - hence .32 ACP and .38 ACP which are really .31 and .36 just as the .38 Special is really a .36 . . . .

    Then, of course, you have the .40 caliber .38-40 Winchester, but that is another story . . . . :D
  4. Xracer

    Xracer *TFF Admin Staff Mediator*

    Calibers is confoozing!!!! :D

    Actually, a caliber is 1/100th of an inch. Sooooo........for instance, 22 caliber should be 22/100 of an inch. 32 caliber should be 32/100 of an inch.

    Then, of course, there are European designations of calibers, which are expressed in the metric system. So...... .308 Winchester is also 7.62x51mm.
    And 8mm Mauser is also 7.92mm Mauser and can be either .318 or .323.

    All of these calibers are nominal (close, but not exact).

    So....all 38's are .357 execpt 38-40 which is .401. And no, you can't fire 9mm (.355) thru a .38 because the cartridge case is entirely different.

    And if you're not confused now, you obviously don't understand the situation! :p

    Seriously, caliber designations are a hodge-podge and many designators are handed down from a century (or more) ago and are only a rough approximation of how things are in the real world.

    I'd suggest you buy a copy of Cartridges Of The World, and read it cover to cover. Then you'll really be confused:
  5. inplanotx

    inplanotx Active Member

    Jan 28, 2002
    Yup, what Xracer said. I have the book and it is just full of information about all cartridges. Great reference book.
  6. Xracer

    Xracer *TFF Admin Staff Mediator*

    And......if you're not confused enough, there are the cartridges with secondary designators like:

    .30-40....which is actually .308. The "40" is it's original loading in grains of blackpowder.

    .30-30....which is actually .308 and would've been loaded with 30 grains of blackpowder if it were a blackpowder round....which it never was.

    .30-06....which is actually also .308. The "06" is the year it was adopted by the U.S. Military, which was 1906.

    .25-06.....which is actually .257 and no, it wasn't adopted by anybody in 1906. It's actually based on a necked-down .30-06 case.

    .250-3000.....also .257 and supposedly had a muzzle velocity of around 3000 feet per second.

    303 British....which is actually .311. Why? I dunno, ask the British.

    .38-40.....which should be 38 caliber with 40 grains of blackpowder....but is actually 40 caliber (.401) with an original load of 38 grains of blackpowder.

    And the list goes on....and on.....and on.... :confused:
  7. 45Smashemflat

    45Smashemflat Active Member

    Oct 6, 2003
    Then you got the 7mm Magnum which is nothing more than the 270 with a belt...... Its all marketing's fault!!! :)
  8. inplanotx

    inplanotx Active Member

    Jan 28, 2002
    I think not. A 270 is a necked down 30-06 case with a bullet diameter of .277". A 7mm Mag is a belted cased cartridge with a bullet diameter of .284". Different head spacing for two different cartridges. 7mm Mag headspaces on the belt while the 270 Winchester head spaces on the case shoulder! :eek: :eek: :eek: :eek: :eek:
  9. Country101

    Country101 Well-Known Member

    Feb 28, 2004
    NW AR
    I'm confused....

    No need to keep explaining. After ten years of explaining, I'd probably end up just as confused and you probably would be by then too. :)
  10. 45Smashemflat

    45Smashemflat Active Member

    Oct 6, 2003
    I was really just funnin' on that one - I know they are not physically the same, but interestingly, ballistically many of the loads are....
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