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excessive clearance

Discussion in 'Blackpowder' started by sslog1, Apr 16, 2013.

  1. sslog1

    sslog1 Member

    I have an 1849 pocket navy revolver made in 1972. There is approx .027 clearance between the barrel and the cylinder. The gun is in good condition. Would it be safe to shoot it using light loads or would it be a hazard?
  2. BlackNet

    BlackNet Well-Known Member

    Think that gap is required for proper operation.
  3. BCRider

    BCRider Well-Known Member

    Blacknet, that is WAY too much by ANY standard. .027 is the thickness of 3 to 4 business cards. A proper gap would be more like .006 to maybe as much as .010. Even then most would consider .010 to be excessive even if it's useable.

    SSlog, is this an open top style? If so then it likely needs to have the arbor adjusted so that the wedge locks the barrel in place properly.

    Sadly this is one aspect that the Italian clones cannot seem to get right. The wedge is supposed to bear off the back of the wedge slot of the barrel and against the forward edge of the slot in the arbor. The front of the arbor is supposed to be pushed by this wedging action into the forward end of the arbor hole in the barrel. At that point the wedge is locked in position by these three contact points. If the gap is wrong at that point then things need to be adjusted to let the barrel come back farther. At the same time that the barrel wedges into place the heel of the barrel to the frame has to make contact with some moderate amount of force but closely enough that it does not try to force the barrel into tilting upward by very much if any.
  4. BlackNet

    BlackNet Well-Known Member

    Doh sorry
  5. sslog1

    sslog1 Member

    BCRider, Thanx for the info. Being a retired mechanical engineer I realize the work that will be involved is not worth it. Guess this revolver won't be shot again soon.
  6. fogg64

    fogg64 Well-Known Member

    What would be the consequences of a wider gap? Loss of pressure/speed? More flame from the gap? Unsafe? or maybe none of these? I forgot, maybe the cylinder will travel forward when it is fired causing a misfire or not.
  7. damoc

    damoc Well-Known Member

    Id love a parts/tinker gun if you want to sell it.

    Fogg64 I think that too much gap could not only cause excesive gas leakage
    and lower velocities but could wind up with bullets jammed in the barrel
  8. 44 Dave

    44 Dave Well-Known Member

    I have an 1860 with close to that much space, I shot it today. It may loose a little, but there is no danger may even be less as the pressure is released.
    Yes there is arbor- barrel - barrel wedge adjustment that could be done. I got a new wedge last week so that if ever I really want to mess with it.
    It shot a 1 3/4" group today at 15 yards!! no rush to change it.
  9. Noz

    Noz Well-Known Member

    Extra smoke and noise and the possibility of some lead spitting. Other than that, no sweat.
  10. J-Bar

    J-Bar Well-Known Member

    This. Keep your shooting companions behind you (rather than beside you) when you touch it off. Otherwise, enjoy!
  11. 44 Dave

    44 Dave Well-Known Member

    Well you guys got me off dead centre, I got to my 1860 barrel gap. I had to "adjust" the lower barrel to frame area as well as wedge to arbor fit. Got it down to.011 from .024 that is tight enough for ball and cap.
    The weather here rain and 33 degrees so an inside project was needed this morning.
  12. BHP FAN

    BHP FAN Well-Known Member

    saweet...I love a story with a happy ending!
  13. drjohn

    drjohn Member

    The loading lever hook jumped off my ASM colt army and everyone was out of stock on a replacement part and craxy on the shipping so I got another ASM barrel off EBay for 30 something. When it arrived it was well abused and needed a lot of fitting, dressing out peen marks from screwdriver blade vs. wedge, and enlarging diameter of the arbor well with dowel and emrycloth. Then the cylinder would not turn until I worked the barrel cone down some. Now my question is how much clearance is needed? The cylinder turns nicely and I can see a sliver of light between. I haven't measured it but I would guess around the short side of five thousanths. I put a few rounds through it and it shoots fine, even truer than the original barrel that shot more high and to the right than I was comfortable with.
    Last edited: Apr 20, 2013
  14. mykeal

    mykeal Well-Known Member

    The answer is:

    Alternatively, .005" to .010" is just fine.
  15. madcratebuilder

    madcratebuilder Well-Known Member

    Open tops need about .008 according to old Colt literature. Tighter can cause cylinder drag. .027 well have more 'flash', I've seen 'new' revolvers with that much gap.

    Smokeless is much tighter, down to .002 on DW's. The face of the cylinder and forcing cone must be perfect to run this tight.
  16. Dan D

    Dan D Active Member

    44 Dave, did you remove metal from the frame, the barrel mating surface or both?

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