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Colt Python Tapered Bore

Discussion in 'Handguns: Revolvers' started by 243winxb, Jul 7, 2018.

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  1. 243winxb

    243winxb Member

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    https://www.americanrifleman.org/articles/2018/6/18/a-colts-python-primer/

    From an article in the June issue of the American Rifleman Magazine.

    How can a barrel be made with a tapered bore? Hammer forging?

    How were barrels made?

    In the 1970s, seen a Python severely lead the bore with a swaged 148 gr lead wadcutter and 2.7 grs Bullseye powder. The barrel slugged at .354"
     
  2. Gordon

    Gordon Member

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    They had a "ball" lap device that was forced down the bore from back to front, I believe Anschutz uses the same process on their match barrels. I don't understand exactly how it worked , Ferriswheel does I believe.
     
  3. 243winxb

    243winxb Member

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    Gordon, ty.

    Have not found any posts where someone slugged it from the muzzle the first inch or so, then slug from the breech and compare the two. Using Cerrosafe to make a cast should work also.

    https://www.thehighroad.org/index.php?threads/the-myth-of-the-silver-ball-treatment.23625/
    "Silver Ball" Treatment" i did find this and others, before starting the thread.

    If the taper is small, less then .001" may not get a correct measurement as lead springs back after sizing.
     
  4. reddog81

    reddog81 Member

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    There are a number of threads out there discussing this subject and I've never read one that has a definitive answer.

    I've read about the silver ball treatment before but it seems that no one can confirm what was used or even what the purpose was. If they were pushing a silver ball through the bore smoothing the lands this would indicate the lands had a consistent diameter.
     
  5. Gordon

    Gordon Member

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    dfariswheel, yup thats the post. He worked for Colt and knows . The Python also has a tighter twist than other .357s and .38s . I miss dfariswheel :( . Like I said I have heard the same story from major match competitors about anschutz who bragged until recently about thier microscopticly "choked" and lapped bores.
    "Yes Virginia, there is, (or at least was) a Silver Ball treatment.

    It was a proprietary Colt manufacturing process used only on Python barrels.

    Colt used this mysterious process on all Python barrels. A Colt worker would use a press to force a silver ball of unknown composition down each Python barrel as a final step.

    I have personally talked to two people who actually saw the process.

    Colt would never reveal just what the balls were made of, but both people I talked to said it looked like a bright silver metal of some sort. One witness told me that after the ball was pressed down the barrel, the bore had a brilliant, mirror look unlike anything he had ever seen before.

    I don't know if Colt still does this, but somehow, I suspect they do."
     
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  6. Jim Watson

    Jim Watson Member

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    A gunmaker's barrel shop foreman once told Harry Pope that. Harry demonstrated on a toolroom gauge standard that it would not.

    Well, they don't make Pythons any more, so I suspect they don't.
     
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  7. 243winxb

    243winxb Member

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    Post 26 , at above link. www.thehighroad.org/index.php?threads/the-myth-of-the-silver-ball-treatment.23625/

    Ballizing, as i think i understand how to make a tapered bore.

    The speed of the ball is varied. Slow, less spring back . Fast, more spring back of the barrel steel.

    In other words , start slow then increase ball speed as it travels down the barrel to the muzzle.

    The lands (bore)would be changed, but would the groove diameter? I would guess groove diameter remains the same?
     
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  8. sgt127

    sgt127 Member

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    My gut tells me it’s a marketing ploy. If you push a ball, of fixed diameter, down a barrel, the size of the hole is going to be the same from one end to the other.

    It may burnish the lands, but, it can’t possibly touch the grooves. If it does, your gun will be a smooth bore.
     
  9. JohnKSa

    JohnKSa Moderator Staff Member

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  10. 243winxb

    243winxb Member

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    JohnKSa , ty for the links. More then one way to get a tapered bore.
     
  11. 243winxb

    243winxb Member

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    The benchrest gunsmiths have said the bore in match grade barrels are not straight. This method , using a reamer may make straighter bores? But seens unlikely that current benchrest accuracy could be improved by a taper.
    From above link.
     
  12. Jim Watson

    Jim Watson Member

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    Harry Pope was not real forthcoming about his methods. Somebody eventually decoded his gain twist markings.
    He said he did not "lead" (lead lap) his taper in place, that he did not put emery in his barrels like other shops did.
    Lots of slug and schuetzen rifles had tapered or choked barrels, formed by controlled lapping.

    Another old time refinement was the progressive depth rifling of the Springfield rifle musket of Civil War era.

    I understand that when you see a target .22 or air rifle that is of enlarged diameter at the muzzle, it is choked due to greater springback of the thicker barrel walls after the rifling button has exited. No extra steps required.

    On this or other gunboard, I have read somebody to say he had or had the use of an air gauge. If we could get him to put it in a Python barrel, we would know what was going on.
     
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  13. Mizar

    Mizar Member

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    Jim, a more "lame" approach would be to swage a lead ball on couple of spots down the barrel - let's say right after the forcing cone, middle of the barrel and at the muzzle. With a good micrometer that (supposedly) .0005" difference can be measured without any trouble.
     
  14. dfariswheel

    dfariswheel Member

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    " He worked for Colt and knows "

    No I didn't.
    I was a watchmaker/gunsmith and specialized in Colt double actions revolvers. I never worked for Colt.

    I'm no machinist but it's certainly possible to taper a bore, probably using some sort of broach.
    I don't what method Colt used but the slight taper gripped the bullet progressively tighter as it passed down the bore.
    That, along with the faster Colt rifling gave the Python better accuracy.

    I also don't know how Colt made the silver ball treatment work, but obviously they knew how to do it because they did do it.
    The ball apparently surface hardened and burnished the bore, and made it uniformly smooth the entire length.
    This probably "ironed out" any imperfections left by machining.

    Colt always made their own barrels and the Colt barrels were always famous for accuracy.
    I suspect that if you could precision gage most any Colt revolver barrel you'd find a slight taper in the bore.
    They only advertised it in the Python.
     
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  15. Gordon

    Gordon Member

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    Thanks and good to see you active.
     
  16. Jim Watson

    Jim Watson Member

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    Broach appears to be the same deal as a ball. When you pull a broach through a hole, it is going to be the diameter of the last cutter throughout.
    There is obviously something I am missing, not being a machinist. Pedersoli advertises tapered bores and broach rifling.
     
  17. 243winxb

    243winxb Member

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  18. Slamfire

    Slamfire Member

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    My 22lr Benchmark barrel, on an Anschutz action, it is a choke bore. The gunsmith hammered a lead lap till he found maximum choke, and cut the muzzle just forward of that location. It shoots well. I can tell the bore is choked by how the resistance increases as a patch goes down the tube.

    I have been told by a barrel maker that broach cut barrels expand as material is removed. This may be the reason for the larger diameter shanks, found on Anschutz barrels. In this picture, showing two different era barrels with different lengths of shanks:

    w94qZNl.jpg

    If the extra diameter adds weight and keeps the barrel ID tighter, than that would account for the shank.

    I do believe that there may be something to the idea that barrel choke improves accuracy. This is based only on a few examples, but my 1937 M70 is exceptionally accurate for a light weight sporting rifle and it has a choke barrel. Resistance to pushing a patch out the barrel noticeably increases in the last four inches of the barrel. It shoot very well, all the way out to 600 yards with a fixed 6X 1970's Burris scope on top.

    vz1IdKz.jpg
    17GGA58.jpg
    EKp6QfO.jpg

    YSI4JZj.jpg
     
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  19. Gordon

    Gordon Member

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    all I can say is WOW! to the old M70!
     
  20. Shimitup

    Shimitup Member

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    Well here's one method to broach or draw a ball through a bore to form a taper. Any method of heating the muzzle end of the bore, cooling the breech end or anything in between. So long as there is a differential temperature from one end to the other. The broach will pass through leaving the bore at the diameter of the barrel at it's present temperature. When the barrel temp is then equalized you then have a tapered bore. The broach also will change as the thermal conduction from the barrel transmits to the broach but keep in mind that the broach being much smaller (and possibly an alloy with a very low coefficient of thermal expansion, Invar is one such alloy) it's diameter will change to a much lesser degree than the barrel.

    One more thought on this is that you naturally begin tapering the barrel while firing the gun as the breech end heats.
     
  21. Jim Watson

    Jim Watson Member

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    Neat, taper induced by varying thermal expansion. I'll take that as a working theory until a Colt or Pedersoli retiree comes along.

    Shank? I call the part pressed or screwed into the action the shank.

    I read about choke or distortion caused by springback after button rifling, nothing about after a cutting operation with a broach.

    I don't know what S&W are doing to their regular production guns now - the monster magnums get ECM gain twist - but for a long time S&W revolver barrels were broached, then lapped. Single point cut rifling was too slow and button rifling would give irregular dimensions of a barrel with asymmetric shape.

    Hammer forged barrels have a lot of internal stresses and there were some interesting bores in barrels turned to contour from hammer forged blanks. This may be why a long series of Steyrs had the hammer marks left and just polished shiny.
    I was looking at pictures from the Arex plant in Slovenia. They use hammer forged barrel blanks machined to shape for their pistols. The blanks are very large in diameter, there are a lot of chips on the floor. I bet they are strenuously stress relieved before turning down.
     
  22. Mizar

    Mizar Member

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    Is it possible that the Ares barrel blanks have a large diameter not correlated to stress relieving, but made like that so they (workers) can have enough material for the locking lugs, as barrels are of one piece design? When hammer forging a barrel it's always easier to left it unfinished with the forging markings - it's not only cheaper, but it emphasizes on the forging process that is viewed by some as superior to the more traditional methods. And one almost always gets a somewhat distorted barrel with modern methods of rifling - it's just the nature of the beast. That's why they invented the barrel straightening presses I believe. And when turning down a barrel blank one gets a slightly larger inside diameter, no argue about that, but with how much exactly? Is the difference really that extreme to require additional treatment, or it can be calculated at the start and produce a perfectly usable service grade barrel without any hustle?
     
    Last edited: Jul 11, 2018 at 3:42 PM
  23. Slamfire

    Slamfire Member

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    Shank was the best term I could think of for the big bulgy thing at the end of the barrel. o_O If this was a sword, I would call it a kilij.

    s715307709555333464_p378_i1_w2000-1.jpg

    s715307709555333464_p378_i8_w2560-1.jpg
    If you have a better term, put it out there.

    If could have been button rifling instead of broach rifling, my memory is not that good you know. I did talk to a barrel maker and asked him those questions and was told cut rifled barrels did not change ID when the OD of the barrel was reduced. But that one of the other techniques did. And the term started with a "B". So it was not hammer forged barrels. :rofl:
     
  24. Jim Watson

    Jim Watson Member

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    I call the end toward the target the "muzzle."
    I have read that button rifle barrels are subject to crawling around if turned without stress relief.
    A broach is a cutting tool that cuts all surfaces of the hole at the same time. What I have seen pictured are gang broaches with many cutters of the same shape but graduated sizes on a shaft. I can't see where a broached barrel would be more subject to movement than a single point cut barrel.
    Trivia: When Mr Garand was designing rifles, the latest in machine tools was the gang broach. He incorporated as many broach cuts as possible for faster manufacture than by lathe and mill.
     
  25. jmorris

    jmorris Member

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    There are a number of ways to rifle a barrel but Jim’s understanding of a broach can be accurate.

    Although some broaches only cut on a single surface, like one for a keyway in a round hole. However, if you have the round hole and want to change it’s shape that is one method.

    Sometimes it can take some distance to get to the final shape as well because “chips” can spoil finish if they have nowhere to go and are forced to burnish the surface.

    2E840E38-C464-4304-9A1D-636DF510B313.jpeg
     
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