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.45 ACP Balistics - Semi-Auto vs Revolver

Discussion in 'Firearms Research' started by Schuarta, Feb 22, 2011.

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  1. Schuarta

    Schuarta Member

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    I just acquired a revolver in .45 ACP caliber, 5-1/2" barrel. I have had a 1911 .45 ACP for some time, with a 5" barrel. Since they both fire the same ammunition, my mind began buzzing with the following puzzle. :confused:

    Using the same box of ammunition for both weapons, would the balistic performance of the bullet fired by the revolver be superior to that fired by the semi-auto? Would the muzzle velocity be greater? Would the muzzle energy be greater?

    The basis of the question is that the .45 ACP cartridge is being held rock solid in the revolver, as it fires, while there is the semi-auto mechanism to operate in the 1911. What percentage of the propellent energy is used to cycle the 1911? What percentage velocity and/or energy improvement might be realized in the revolver?
     
  2. Gryffydd

    Gryffydd Member

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    In equal barrel lengths a revolver will typically have less velocity due to the barrel cylinder gap.
    The semi auto action part doesn't really come into play as the bullet has already left the gun by the time the action really gets moving.
    Also remember that barrel lengths in revolvers are measured differently than a semi auto. The measurement for a revolver does not include the chamber as it does with semi-autos.
    Between those guns I would not expect to see much of a velocity difference.
     
  3. Jim K

    Jim K Member

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    Not enough difference to worry about or even notice; the b/c gap will cause less difference than between different cartridges out of the same box.

    The 1911 is cycled by recoil, not directly by pressure, so that has no bearing on things.

    Jim
     
  4. rcmodel

    rcmodel Member in memoriam

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    +1

    Any decrease in velocity due to the barrel/cylinder gap is made up for by the 1/2" longer barrel and cylinder length.

    Your 1911 has a 5" barrel including the chamber.
    The revolver has a 5 1/2" barrel plus another 1 1/2" of cylinder with the chambers in it.

    It might prove to be faster then the auto, but not because of the auto using up power to operate.

    As noted by Gryffydd, the bullet is already down range before much of anything takes place with the pistols recoil operation.

    rc
     
  5. Jim K

    Jim K Member

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    "the bullet is already down range before much of anything takes place with the pistols recoil operation"

    Not quite so. High speed photos show the slide back about 1/4" and dropdown starting as the bullet is leaving the barrel. Remember that backward recoil of the barrel/slide unit started when the bullet started moving forward, and that recoil has been taking place while the bullet has been moving down the barrel. (That is why front sights have to be made to take recoil into consideration.)

    Jim
     
  6. Jim Watson

    Jim Watson Member

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    Theory aside and sorry it is not with a more usual powder but it is what I can readily find in my notes as a direct comparison...
    .45 ACP 230 gr LRN + 5.0 gr Green Dot
    1911 w 5" Briley barrel -- 792 fps
    S&W M25-2 sawn to 5" -- 752 fps
     
  7. Dr.Rob

    Dr.Rob Moderator Staff Member

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    I don't recall much difference on the chronograph between a 1917 Colt New Service and a 1911 Government model. I was suprised at how dead even they are. I shot HydraShocks, FMJ and lead SWC's through both a lot... never saw much variation between the platforms, not enough to note one load as better in either platform.
     
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