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Thread: 41 colt to 38-40 ?

  1. #1
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    Default 41 colt to 38-40 ?

    Has anybody here converted (okay, added a second cylinder) a Colt SA in 41 Long Colt to 38-40?

    It seems like the best way to keep an old 41 shooting without going through the reloading troubles that a 41 has.

    How big of deal would this conversion be?

  2. #2
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    Swapping cylinders is a rather common modification for the SAA. If you haven't done it, I would recommend getting the Kuhnhausen manual for the finer details of fitting and timing.

    http://www.gunbooks.com/colt_sa.html
    Jim H.

  3. #3
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    The original heel-base bullet for the .41 Long Colt had an outside diameter of .410", while the 38-40 uses a nominal bullet dia. of .401". You may be ok with very soft bullets, but hard cast will just lead up your bore and give poor accuracy.

    David
    Montezuma, IA

  4. #4
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    Quote Originally Posted by 38_Cal
    The original heel-base bullet for the .41 Long Colt had an outside diameter of .410", while the 38-40 uses a nominal bullet dia. of .401". You may be ok with very soft bullets, but hard cast will just lead up your bore and give poor accuracy.

    David
    Montezuma, IA

    I think there has been a lot of confusion about doing this for the reasons you are mentioning. I saw one at a gun show recently and the owner said it functioned quite well.

    Maybe this can explain it.

    www.en.wikipedia.org/wiki/.41_Long_Colt

  5. #5
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    Radkins, I hadn't run into any references to a smaller diameter (38-40 sized) bore before. Thanks for the link. Huntinguy, you will probably want to slug the bore on your Colt to determine which version you've got before making the investment in the new cylinder!

    David
    Montezuma, IA

  6. #6
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    they both have the same bore dia. so all you change is the cylinder that is what mike venturino did in his book shooting the colt single actio

    skeeter skelton also talks of doing the same thing. he even had a .41 that some one reamed the cyl. out to .38-40

  7. #7
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    Quote Originally Posted by radkins
    I think there has been a lot of confusion about doing this for the reasons you are mentioning. I saw one at a gun show recently and the owner said it functioned quite well.

    Maybe this can explain it.

    www.en.wikipedia.org/wiki/.41_Long_Colt

    if that really is the case, and i was going to have a 38-40 cylinder fitted, i would just have the cylinder machined to match the bore of the revolver, and then have a set of reloading dies machined to match as well.

    andy b.

  8. #8
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    Slugging the bore is a good idea to see just what you have. Manufacturing procedures and tolerances were not what they are today and there is more variation in bore dimensions than in today's guns.

    With that knowledge, if reloading, a sizing die can be used to size the bullets before loading. Custom dies are not needed.

    Do keep in mind that any of the SAA's have a collector value, and load so as not to destroy the gun. Much enjoyment can be had with light loads and lead bullets. Any modifications should be to the replacement cylinder to allow returning the gun to it's original condition by simply re-installing the original cylinder.
    Jim H.

  9. #9
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    Default Thanks

    38 cal. I was trying to get away from the healed bullets and not shoot the .387 dia. undersized “minie”s)

    JCHannum, I was trying not to affect the collectors’ value of the gun. That is why I was thinking I could get away with the 38-40. For some reason I thought they had the same bore. I was confused…

    I think I will check around and see if I can find some hollow base bullets for the 38-40 before I give up on the conversion. At least then the bullets should be closer to bore size and not rattle down the barrel.

    Thanks all.

  10. #10
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    If you can find a second cylinder, ream it out as needed. I would make up some dummy cartridges with bullets the proper diameter needed for your barrel (groove dia. + .002") if it is larger than the throat of the chambers. You can, if necessary, open up both the chamber throats and the necks with very careful use of chucking reamers. If necessary, open up a sizing die to accomodate the larger diameter bullets. To open up a mold, use a small boring bar for the bands in it, at least on the bottom two bands. Cast a few bullets first to determine what diameter your alloy casts in your mold, determine how much you need to enlarge the mold, and bore it out by that much. Of course, if you really want to make a HSM project out of this, get a smaller diameter single cavity bullet mold, say, for a .30 caliber rifle, and make up a hollow base bullet mold from it. The original base of the bullet becomes the nose of the new design.

    Keep us informed of your progress, please!

    David
    Montezuma, IA

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