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Cylinder Gap

Discussion in 'Handguns: General Discussion' started by KevinR, Jan 21, 2010.

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  1. KevinR

    KevinR Member

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    How much space is too much, between brl and cyl???
     
  2. rcmodel

    rcmodel Member in memoriam

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    Between .004" - .008" is about perfect/normal.

    More then .010" is, IMO, too much.

    rc
     
  3. dfariswheel

    dfariswheel Member

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    Recently, S&W has been passing gaps as much as 0.012" as "in spec".
     
  4. EddieNFL

    EddieNFL member

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    I'm with RC. When DW was producing revolvers, the feeler gauge supplied was 0.006" I used to set mine at 0.002" for silhouette matches. Had to keep a brush on hand to clean the cylinder face.
     
  5. hardluk1

    hardluk1 member

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    Another DW owner that sets his 357 and 44 at .002. Even may Charter Arms is at .002 and run flawless.
     
  6. KevinR

    KevinR Member

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    Very interesting, I was just wondering because my S&W mod 60 357 is .008 No wonder it is so darn loud.
     
  7. DWFan

    DWFan Member

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    A large barrel gap can sometimes indicate that the cylinder isn't square or true in the frame. Best to measure from both sides and at several chambers. Some Dan Wessons can have the barrel tightened down against the cylinder, the gun raised up to a light and the barrel unscrewed until the barest sliver of light appears....and still work smoothly. Actually, I haven't seen one that couldn't as long as the cylinder face is kept clean.
     
  8. unspellable

    unspellable Member

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    Nominal for most of the Dan Wessons was 0.006. For the long frame SuperMags it was 0.003. Since the gap is adjustable, I've run a series of tests over the chrono with a 22 DW and a 44 Mag DW. When the gap gets to 0.012 the revolver will begin to spit crap back in your face.

    A couple of considerations. The cylinder face is not a perfect plane at a perfect normal angle to the axis. The cylinder gap should be measured at the chamber where it is tightest if there is a detectable difference from chamber to chamber.

    For serious work where reliability is the primary concern the gap should be in the 0.005 to 0.008 range with 0.006 being optimum.

    For plinking, small game or deer hunting where reliability is not life or death it can be a bit tighter. Taking it down to 0.003 presumes a premium grade revolver that has a dead true cylinder face and minimal end play.

    I think S&W allowing it to go to 0.010 stinks. And going to 0.012 is beyond the pale when you get crap blown back in your face.

    Surprisingly, the cylinder gap does not have as much effect on velocity as you might suppose.
     
  9. Jim K

    Jim K Member

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    You don't want it too small, either. The problem is not dirt or fouling but of binding caused by expansion of the cylinder from heat. I have seen a revolver with a very small B/C gap quit after firing as little as two cylinders.

    Jim
     
  10. Bob79

    Bob79 Member

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    According to Ruger, .010 is within Spec. All of my revolvers seem to be between .006 and .009
     
  11. The Lone Haranguer

    The Lone Haranguer Member

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    I had a M66 whose gap was near or at (possibly exceeding) this. (I didn't formally measure it, just "eyeballed" it.) The cylinder blast was bigger than the muzzle blast. I had them correct it.
     
  12. 340PD

    340PD Member

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    I just checked four of my freshly cleaned Smiths. All were at exactly .004. Two were from the performance center and the other two were off the shelf snubbies.
     
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