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? Ream Oval Chambers on C&B Revolver ?

Discussion in 'Blackpowder' started by randys, Jul 15, 2019.

  1. randys

    randys Member

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    I measured cylinder chambers of 2nd Gen Colt 2nd Dragoon. Used a cheap hole gauge and a caliper. Oval chambers: 0.442" X 0.448".

    Each chamber, axis measured on a line running from center of chamber to center of arbor hole, 0.442".

    Measured perpendicular to line above, 0.448".

    Does it make sense to ream the chambers to consistent dimensions? Can it be done by hand, (how would you get pilot to fit)? How did they manage oval chambers, (.442" drill !?)

    I haven't shot it, I am sure of the measurements, and, yes, each is oval in the same way/dimensions/orientation ("consistent").

    Since even 0.448" mouth would be .010" to .008" under barrel groove diameter (.456 to .458"), maybe I ream for a .458 chamber diameter, (and custom bullet mold.) Bore, .440".

    Thoughts?
     
    Last edited: Jul 15, 2019
  2. mcb

    mcb Member

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    First up would be to double check your measurement hardware against known good dimensions, ie have it calibrated. You admit yourself it's a cheap hole gauge. Small hole ID's are notoriously hard to measure accurately.

    After that double check of measurement gear if the results are still the same it sounds like it was drilled/reamed and either residual stress in the metal caused the chambers to distort or potentially a poor quench and temper caused the chambers to distort.

    Slug the barrel and then ream to appropriate chamber diameter.
     
  3. denster

    denster Member

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    I would suggest that you do not have oval chambers and that the difference in dimensions is due to your equipment and measuring methodology. You could easily verify this with your small hole gauge by taking setting the larger dimension of .448 re-insert it in the hole and attempt to rotate it. If it rotates the hole is round not oval as the gauge contact points would not clear the smaller diameter.
     
  4. beag_nut

    beag_nut Member

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    What you need is an I.D. micrometer in the proper range, i.e. 0-1". Calipers will only "get you into the ball park". The hole gauge, even if it was a Starrett, depends too much on user "feel".
    What "mcb" said about the cause is very appropriate.
    What caused you to check the chambers in the first place? Uneven shaving of a round ball, etc.?
     
  5. randys

    randys Member

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    I am very confident in my technique and equipment to measure a "significant" oval shape to the chambers. Spent much time on each chamber, changing depth, rotating, resetting tools to ensure consistency. No more difficult than reading the meniscus in a burette.

    Taking measurements precise and accurate enough for a machinist to start work was not the goal. Machinist will take their own measurements.


    beag_nut: Why? Various reasons. Because none of my revolvers fit the "rule of thumb" round ball size. Because I seated ball in each chamber of another revolver, drove them out with rod through nipple seat, and found the "ring" on one side of ball was double wide and on other side did not exist. Ball just rests against chamber wall. Explains chain fires, and why I asked about oversized ball in another post, and why I don't like beveled chamber mouths

    Because of the differences between chamber and groove diameter in many older reproduction guns (deep rifling). There was a reason designers of BP guns have deep rifling relative to the .004" standard of modern smokeless guns. Today, shallow rifling seems to be standard in Italian revolvers; is that so they can claim good chamber-to-groove diameter, or does deep rifling not really matter?

    Anyway, ream it by hand and is it worth it questions still stand. Thanks for a "why it happened" reply.
     
  6. skeeterfogger

    skeeterfogger Member

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    Have read that .449 is pretty much it for a .44 cal.. but some, including me, have gone up to .453. Slug the barrel and measure. .001-.002 over is plenty for 99% lead. My advice on reaming is to get several reamers from desired diameter and hair under and 2 hairs under. If you want .453 and ream with .453 you might end up with .454 or .455. Plus it's way easier to remove little at a time. Might also consider only reaming to depth the projectile rams to plus maybe 10%-20%. Just to make it simple.
     
  7. J-Bar

    J-Bar Member

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    I expect an experienced machinist/gunsmith would find it very challenging to correct that mistake. I doubt you would find one that would guarantee perfect results, and even then it could get expensive. I can't think of a way to ream it by hand and get precise results.

    I know it is not what you want to hear but if it were mine I would sell it and buy one without such a manufacturing defect. Or if you like the looks of this one, keep it for a wall hanger. I just hate to see you throw money at a defective gun. There might be a parts gun somewhere with a replacement cylinder with the correct dimensions, as another option.
     
  8. 4v50 Gary

    4v50 Gary Moderator Staff Member

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    If it's oval, then the machine that bored the hole is worn.
     
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  9. skeeterfogger

    skeeterfogger Member

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    A drill press, bolted down vice, plenty oil and patients.
     
  10. treemaker

    treemaker Member

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    The reamer will follow the existing hole. If you ream the cylinder bores round how do you know the cylinder bore center line and the barrel bore center line will match?
     
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  11. 45 Dragoon

    45 Dragoon Member

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    If the OP doesn't want to fit a new Uberti cylinder, a converted Dragoon is always an excellent option!!

    Mike
     
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  12. skeeterfogger

    skeeterfogger Member

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    There are ways.
     
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