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Thread: 38 Colt conversion of .36 caliber small frame Colt percussion pistol

  1. #1
    Boolit Mold
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    38 Colt conversion of .36 caliber small frame Colt percussion pistol

    Please excuse this posting if I have put in up on the wrong forum.

    Has anyone on this forum considered conversion of the small frame 1862 Colt pocket Navy to 38 long Colt? Of course, I only referr here to Italian reproductions. Checking cylinder dimensions of a Uberti pocket Navy in my collection it appears boring that rebated cylinder through to 0.375 would leave remaining metal at the rear of the cylinder perilously thin. I initially thought this could be done safely since I have seen original small frame Colt pocket Navy pistols (36 cal) converted to the 38 Colt cartridge offered for sale on antique gun sale websites. After taking measurements I question if this kind of conversion is possible or advisable. Also wondering how such conversions were done and apparently frequently used 130 years ago.

  2. #2
    Just because it has been done, does not mean it should be done. So No. heel No! to that conversion... uncle mike in ct

  3. #3
    Boolit Master
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    I was just reading about converting cap and ball to cartridge the other day.
    https://www.guns.com/news/2012/12/13...sion-revolvers

  4. #4
    Boolit Master
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    .38 Short Colt...m-a-y-b-e...

  5. #5
    Even on the 1860's a lot of bolt notches broke through.
    Doesn't someone make a conversion cylinder for that revolver?

    AntiqueSledMan.

  6. #6
    Boolit Mold
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    Good point. My guess is drilling a Pocket Navy cylinder to accommodate the 38 long (or short) Colt cartridge would result in opening the base portion of all the bolt notches. Still wondering how this apparently got done in the 1870s. Cimarron appears to be making a reproduction Pocket Navy in .38 acp. Although the case dimensions of this cartridge are similar to 38 LC the case diameter is about .005 larger meaning the cylinder has to be drilled even larger. It looks like Cimarron only makes the pistol and not conversions for other reproductions of the Pocket Navy.
    Last edited by vetpathdoc; 02-03-2020 at 11:08 AM.

  7. #7
    Boolit Mold
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    I know there's lots of machine shop talent on this forum so I guess I posted my original comment to see if anyone ever attempted a conversion like this. I found this photo of what looks like a Mason-Richards, Colt factory conversion of a Pocket Navy. The rear portion of the cylinder wall looks dangerously thin to me. I know these conversions were done for black powder cartridges, but I wonder if there were safety issues with some of these conversions, especially those done on the small frame models.Click image for larger version. 

Name:	2-Original Pocket Navy conversion.JPG 
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  8. #8
    Hey vetpathdoc,

    I measured the cylinder diameters of my Pietta 1858 (CL/2013), D=1.590".
    My Howell (2014) 44 Colt Conversion cylinder, D=1.625".
    Not sure if that helps any.

    AntiqueSledMan.

  9. #9
    Boolit Mold
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    Thanks Sledman - At this point I would be more interested in comparing cylinder dimensions of .36 caliber original and reproduction, small frame Colts like the 1862 Pocket Navy.

  10. #10
    Boolit Master
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    Quote Originally Posted by vetpathdoc View Post
    I know there's lots of machine shop talent on this forum so I guess I posted my original comment to see if anyone ever attempted a conversion like this. I found this photo of what looks like a Mason-Richards, Colt factory conversion of a Pocket Navy. The rear portion of the cylinder wall looks dangerously thin to me. I know these conversions were done for black powder cartridges, but I wonder if there were safety issues with some of these conversions, especially those done on the small frame models.Click image for larger version. 

Name:	2-Original Pocket Navy conversion.JPG 
Views:	7 
Size:	50.0 KB 
ID:	256008
    If you make a new cylinder rather than bore out the old one - most of these capguns you can squeeze an extra twenty thou or so of cylinder wall - take a little out of the frame - tighten the tolerances up - you be surprised what can be done
    Did a remmy once to 44/40 and found enough extra cylinder diameter that I ended up stepping the barrel threads 50 thou to get it back in line

    That little colt would make a dead cool 22 - but too easy and you could buy a ruger bearcat for half the cost ............

    Trade it off for one in 32 and convert that ?

    I have one of these and its stayin just the way it is - it might get a pettifogger workover one day - but not a conversion.

  11. #11
    Boolit Mold
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    Quote Originally Posted by indian joe View Post
    If you make a new cylinder rather than bore out the old one - most of these capguns you can squeeze an extra twenty thou or so of cylinder wall - take a little out of the frame - tighten the tolerances up - you be surprised what can be done
    Did a remmy once to 44/40 and found enough extra cylinder diameter that I ended up stepping the barrel threads 50 thou to get it back in line

    That little colt would make a dead cool 22 - but too easy and you could buy a ruger bearcat for half the cost ............

    Trade it off for one in 32 and convert that ?

    I have one of these and its stayin just the way it is - it might get a pettifogger workover one day - but not a conversion.
    Whoa Indian Joe - "make a new cylinder"??. Now there's a project. Since there's no CNC machine in my basement making cylinders is bit more biting off than I can chew even though "buyin" has never been nearly as much fun for me as "buildin".

  12. #12
    Boolit Master
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    Quote Originally Posted by vetpathdoc View Post
    Whoa Indian Joe - "make a new cylinder"??. Now there's a project. Since there's no CNC machine in my basement making cylinders is bit more biting off than I can chew even though "buyin" has never been nearly as much fun for me as "buildin".
    might surprise you what you can do if you think your way through it
    pre ww2 nutall lathe and a chinese drill press at the time (many moons ago)
    centre bored and turned the blank in the lathe, marked it out by hand and drilled the holes using the drill press, made a chamber reamer from an old hand tap by grinding to shape on the lathe (didnt have the skill required to heat treat a reamer) reamed it on the drill press - marked the locking notches through the bolt hole with the cylinder assembled and a locator rod down the barrel, cut the notches by eye using the drill press and a small woodruff key slot cutter.
    That one is long gone to the crusher, we now need a ministerial permit to hold any cartridge handgun over 38 cal unless its a proper capgun - so I have a nice pigeon pair of stepped cylinder capguns - 1851 navy in 44 (yeah I know no such thing originally but I like the modern version) and a pocket navy 38.

  13. #13
    Boolit Master
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    The originals were built using a different hand and ratchet. Colt had some failures (with many of their models) but they continued on. The new cf Pocket 36s are chambered for the .380 or 9mm Kurz. The 38 ACP is way to much cartridge for the little cylinder. I would not be surprised to find Uberti beefed up the frame and cylinder as they did when they built 45 long Colt versions of the 1860.

    Kevin
    Knowledge I take to my grave is wasted.

    I prefer to use cartridges born before I was.

    Success doesn't make me happy, being happy is what allows me to be successful.

  14. #14
    Boolit Mold
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    Quote Originally Posted by indian joe View Post
    might surprise you what you can do if you think your way through it
    pre ww2 nutall lathe and a chinese drill press at the time (many moons ago)
    centre bored and turned the blank in the lathe, marked it out by hand and drilled the holes using the drill press, made a chamber reamer from an old hand tap by grinding to shape on the lathe (didnt have the skill required to heat treat a reamer) reamed it on the drill press - marked the locking notches through the bolt hole with the cylinder assembled and a locator rod down the barrel, cut the notches by eye using the drill press and a small woodruff key slot cutter.
    That one is long gone to the crusher, we now need a ministerial permit to hold any cartridge handgun over 38 cal unless its a proper capgun - so I have a nice pigeon pair of stepped cylinder capguns - 1851 navy in 44 (yeah I know no such thing originally but I like the modern version) and a pocket navy 38.
    Thanks, Indian Joe - my hat is off. Exactly the sort of comment I was hoping to hear. My basement machine shop is pretty minimal by today's standards, yet not terrible considering what was around in 1870. I agree, a lot of home modifications can be done IF one takes his time and works slowly. BTW, since the 38 short and LC are straight cartridges, couldn't chambering be done with an appropriate-sized reamers? One thing still puzzling me though is how you accomplished making the cylinder rachets. On a side note I've wondered why there are so few photos of the machinery in the old Colt Hartford factory. I'm guessing Sam Colt and those who ran the place after his death were very protective of the manufacturing processes going on inside.
    Last edited by vetpathdoc; 02-07-2020 at 08:14 AM.

  15. #15
    Hey vetpathdoc,

    One could probably get away with a straight reamer from McMaster Carr.
    But I would think that a .002" taper would be much better for extraction of cartridge.
    Probably could accomplish this with polishing, but it would be time consuming.

    AntiqueSledMan.

  16. #16
    Boolit Master
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    Quote Originally Posted by vetpathdoc View Post
    Thanks, Indian Joe - my hat is off. Exactly the sort of comment I was hoping to hear. My basement machine shop is pretty minimal by today's standards, yet not terrible considering what was around in 1870. I agree, a lot of home modifications can be done IF one takes his time and works slowly. BTW, since the 38 short and LC are straight cartridges, couldn't chambering be done with an appropriate-sized reamers? One thing still puzzling me though is how you accomplished making the cylinder rachets. On a side note I've wondered why there are so few photos of the machinery in the old Colt Hartford factory. I'm guessing Sam Colt and those who ran the place after his death were very protective of the manufacturing processes going on inside.
    I think I used a small cutoff wheel on a dremel to make the ratchet - and hand filing and multiple fit and try
    Dont have access to straight reamers other than expensive mail order (I see them advertised in your country but shipping here is more than the reamer cost - have since made a couple from grade five HT bolts for other jobs)

  17. #17
    Boolit Master
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    Quote Originally Posted by AntiqueSledMan View Post
    Hey vetpathdoc,

    One could probably get away with a straight reamer from McMaster Carr.
    But I would think that a .002" taper would be much better for extraction of cartridge.
    Probably could accomplish this with polishing, but it would be time consuming.

    AntiqueSledMan.
    Again might surprise you how quick that will go - make a split mandrel for the drill chuck and wrap good quality emery paper till its a tight fit in the hole - you will take a couple thou out of there in seconds!

  18. #18
    Boolit Mold
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    Hey Indian Joe - thanks again for all those useful tips. Sounds like you have lots of practical machine shop experience. From a few of the terms used in your posts I'm sensing you live on the other side of the pond. BTW - still getting a chuckle from your use of the term "capgun" for a cap a ball gun. Although they had a relatively short life span in gun development history (1847-65?) I still think they are some of the most attractive hand weapons ever made.

  19. #19
    Boolit Master
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    Before CNC (I was there), a dividing head was used on a milling machine to do all the set-ups involving things like cutting rachets, gears, anything that involved evenly cutting in parts of a circle. There are also indexing heads for a mill. Five and six-sided collets are available to use for certain set-ups. The machinist sites probably have many ways to do such setups.

  20. #20
    Boolit Master
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    Quote Originally Posted by vetpathdoc View Post
    Good point. My guess is drilling a Pocket Navy cylinder to accommodate the 38 long (or short) Colt cartridge would result in opening the base portion of all the bolt notches. Still wondering how this apparently got done in the 1870s. Cimarron appears to be making a reproduction Pocket Navy in .38 acp. Although the case dimensions of this cartridge are similar to 38 LC the case diameter is about .005 larger meaning the cylinder has to be drilled even larger. It looks like Cimarron only makes the pistol and not conversions for other reproductions of the Pocket Navy.
    .38 ACP?

    ...runs at about 26000 PSI compared to the 12 or so thousand PSI of .38 Long Colt...so, basically twice the Pressure...

    Do you maybe mean .38 S & W?

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