How does a single action revolver (blackhawk) hold a rimless cartridge like 45 acp, 30 carbine or 9mm?

If these cartridges are rimless, how come the cartridge doesnt fall through the cylinder bore? If a single action revolver can hold a rimless cartridge, why cant a double action revolver? I realize the extraction is easier with a single action but I'm refering only to the cylinder holding the round.


Yes I know about moon clips. So the moon clip is needed strictly for the extraction of the spent cases and not to hold the round in place? I did not know there is a ridge inside the bore that the cartridge "Head spaces" on. I have heard that term before but didnt know what it means.

5 Answers

  • C T M
    Lv 7
    9 years ago
    Favorite Answer

    Rimless cartridges headspace on the case mouth. Inside the cylinder chambers you'd see a slight ridge, this is what the cartridge headspaces on.

    Double action revolvers can and do take rimless cartridges, they use moon clips and half moon clips. The new Charter Arms Rimless Revolvers use a complicated system of springs to hold rimless cases in the cylinder.

  • 9 years ago

    Cane Toad nailed it.

    The term headspace will generally refer to how the cartridge is held in the chamber. So, on a rimmed cartridge, it is going to be held in place by the rim, with a countersunk area at the rear of the chamber. The rimless cartridges will be held in place in the forward portion of the chamber, near the bullet and forward portion of the cartridge case.

    Ruger is able to do this since the shells are extracted through the use of an ejector rod that pushes them out one at a time from the front of the chamber. Double-actions revolvers require a moon clip because the cartridges are ejected from the rear of the chamber area.

  • Anonymous
    9 years ago

    They headspace on the case mouth. A double action revolver can hold a rimless cartridge if it is designed to do so.

    The illustration shows a 1911 barrel but a revolver barrel would be the same principle.

  • 9 years ago

    Half-moon clips. DA revolvers use them as well.

    Edit: Sorry guys, I forgot to mention the method that rimless cases use to headspace.

    And NO, sometimes the moon clips perform both functions.

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  • Karle
    Lv 7
    9 years ago

    the moon clip HOLDS the rounds and is NOT just for removal ....on firearms that use them....

    but yea most revolvers that take rimless cartridges the cylinder is machined with a ridge.......

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