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Walker with a different twist --- .45 BPM (.45 Black Powder Magnum)

Discussion in 'Blackpowder' started by ClemBert, Oct 11, 2010.

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  1. ClemBert

    ClemBert Member

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    Okay cap-n-ballers….don’t hate me. I decided that I wanted the option of shooting cartridges in my Walker in addition to shooting cap-n-ball style. I purchased a Kirst Konverter and had a channel cut in the recoil shield to allow for breech loading of cartridges. There are a couple of things about converting a Walker to shoot .45 Colt that always bothered me. (1) The .45 Colt cartridge only allows for a maximum of 40 grains of BP whereas the Walker in cap-n-ball style can hold up to 60 grains. (2) The relatively short length of the .45 Colt cartridge means there is quite a bit of bullet jump before the projectile gets to the forcing cone. Seems that with the convenience of a cartridge conversion you can’t have your cake and eat it too. I thought I’d do something about it (because I like cake) to get a little bit more flexibility when it comes to cartridge shooting. Sheesh, do I have too much time on my hands or what? FWIW, you non-engineers should know that most of us engineers spend way to much time thinking about solving problems even if they don’t really exist and we have to create a theoretical problem out of thin air.

    Enter the .45 BPM. This cartridge addresses the two issues I mentioned above. (1) The .45 BPM can hold 60 grains of BP. (2) The cartridge is longer and therefore the projectile can sit much closer to the forcing cone. There was a little work that had to be performed on the Kirst Konverter. The rim recess diameters had to be increased slightly and each chamber had to have the rebate depth increased. It will still hold .45 Colt cartridges.

    This is not an idiot proof solution. Any self proclaimed idiot or bed wetting tree hugger may want to stop reading here. Cartridge reloading, in general, isn’t idiot proof. Attempting something foolish with any cartridge reload could lead to disastrous results. I say this because I don’t need to read someone post “What’s going to happen if someone accidentally loads the cartridge full of Bullseye and tries to shoot it out of a Walker?” Well, what do you think is going to happen? Probably a junior version of if someone loads up a .45 Colt cartridge with Red Dot and tries that in a Walker. Right?...just a smaller mushroom cloud.

    Note that no where in this thread will you see me advocate loading up a .45 BPM cartridge with 60 grains of BP and firing it from a Walker. I only mention the maximum capacity because I know someone will ask. It is possible it could make for a fun little carbine rifle cartridge. Without thorough testing and analysis I have no idea what kind of pressure may be generated. It depends on the firearm, the amount of BP used, and the weight of the projectile to mention a few important factors. I am confident, however, that there is room for shooting more than the 40 grain limit of a .45 Colt in the .45 BPM. There are a few BP bullets that may be of interest to try out with more than 40 grains of BP. Specifically, one example is a 150 grain BigLube .45 caliber bullet that may be a good substitution for a round ball. Speaking of round balls, there isn’t any reason you couldn’t load up some “gallery loads” using your typical soft lead round ball. When I say “gallery load” I’m really not talking about in the traditional sense. Rather I mean it as a cartridge loaded with a round ball. A round ball with 50 grains of BP just may be a decent substitute for shooting a Walker cap-n-ball style with a similar load of BP.

    I still plan on shooting this Walker cap-n-ball style. I just thought I’d mix it up a bit by having the option to shoot the .45 BPM cartridge in it too. I haven’t shot the Walker yet with a .45 BPM cartridge. I’m still waiting for the weather to cool down a bit more. ClemBert’s shooting range looks like a hayfield right now. The last hay cutting for the season should be soon then I’ll be good to go. The first loads will most likely be 40 grains of FFFg, grits for filler, and a 250 grain BigLube bullet. Without further adieu, here are a few pics for your viewing pleasure.

    .45 BPM (left) .45 Colt (right)

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    Last edited: Oct 11, 2010
  2. bubba15301

    bubba15301 Member

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    what case did you use?
     
  3. ClemBert

    ClemBert Member

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    .460 S&W Magnum.
     
  4. Pulp

    Pulp Member

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    I've considered doing that with my R&D conversion. Those extra long cartridges would really raise eyebrows at a SASS match! Never have done it, I don't think the Walker frame would hold up very long with max loads, and 1000fps is the speed limit for revolvers in SASS. Might make a heckuva hog or deer load though.

    Good luck with the project and keep us informed.
     
  5. Olmontanaboy

    Olmontanaboy Member

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    Outstanding! I love it!
     
  6. ClemBert

    ClemBert Member

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    Yup, I think the 255 grain bullets with 60 grains of BP should be reserved for some kind of novelty carbine rifle. The 150 grain BigLube bullet probably comes closest to mimicking a 141 grain round ball projectile. That bullet may or may not work well with a 50-54 grain load. There are a number of issues at play that I won't get into right now. The problem with a large bullet and lots of powder is the pressure that could/would develop.

    I haven't shot at a SASS event. I don't know if this would even be "legal" there. I assume not. But you're right. Even with a 35 grain load and a 250 grain bullet you'd probably get some weird looks with the cartridges sitting on the table.

    BTW, I am aware of a gunsmith working on a carbine rifle based on a Walker and a 45-70 casing cut down to length. I'd love to hear from which ever one of y'all is working with that gunsmith.
     
  7. Tommygunn

    Tommygunn Member

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    The mid 19th century version of Dirty Harry would love that gun!!
    And even I am drooling ....
     
  8. flibuste

    flibuste Member

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    Hello,

    Very nice job !!

    FYI I have shot Lee 255grs bullets with 30grs BP with good results in a Walker


    This load has not stressed the frame ( but I did not test on the long run)


    [​IMG]

    Have fun
     
  9. Oyeboten

    Oyeboten Member

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    Very nice ClemBert!


    Let us know what the Chrony says?
     
  10. Foto Joe

    Foto Joe Member

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    ClemBert, that thing is "Sweet"!! It just makes me want to go to my local indoor range and shoot it. Of course I would be wearing a breathing apparatus and carrying a fire extinguisher to put out my target.
     
  11. Packman

    Packman Member

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    Clembert, that's pretty sweet. My brother is an engineer, I know how you all are with your solutions looking for problems.

    Looks like a very well-done setup. Let us know how it shoots!
     
  12. Nicodemus38

    Nicodemus38 Member

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    im advocated simply drilling the original or kirst cylinder out and simply using a 454 case loaded with original bp loads for the colt walker that are proven safe in the gun.
     
  13. Oyeboten

    Oyeboten Member

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    The diameter of the Ball of course, where it fits into the Cartridge, vis-a-vie, the diameter of the Barrel, is a consideration of course.


    The .460 S & W Magnum Case, normally holds a .452 Bullet.


    Maybe could be fire-formed to instead hold a .454 or .455 Bullet if Cylinder Chambers allowed.

    BP makes enough pressure to Fire-Form a straight walled Cartridge Case to be chubbier, if one needs it to be.



    I know in my Walker, a .452 Ball would just roll down through the Barrel.



    Jus' thinking out loud...
     
  14. ClemBert

    ClemBert Member

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    I considered the .454 Casull casing. It failed the criteria I had set. By my calculations if a .45 Colt holds 40 grains of FFFg then a .454 Casull casing will only hold about 44 grains (about 10% more). The .45 BPM will hold 58 - 60 grains. Also, the .454 Casull casing still leaves quite a gap to the forcing cone.
     
  15. arcticap

    arcticap Member

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    Last edited: Oct 12, 2010
  16. ClemBert

    ClemBert Member

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    Yes, I previously mentioned that there are some "issues at play".

    The Kirst Konverter for the Uberti Walker is designed for 0.452 diameter .45 Colt bullets. As such there is reliance on obturation of the bullet. That is, the base of the bullet flaring under the pressure. This seals the bore. Typically, softer lead bullets do a better job of this. The bore diameter (lands) of my Walker is 0.439. A 0.452 bullet will not roll through the barrel. However, because my groove diameter is greater than 0.452 obturation is important. Alloy content could be important. Keep in mind that on my cap-n-ball cylinder the chambers are 0.450 so a 0.452 bullet is actually larger than a round ball to be fired cap-n-ball style.

    With regards to 0.454 round balls there are a couple of ways to make them work. First, the .45 Colt reloading dies do have an expander die that will flare out the cartridge. Also, as you indicated, it may be useful to skip using the .45 Colt resizing die. Basically, just use unsized fired brass. Not only is this a consideration for loading a 0.454 round ball but some thought has to be given as to whether or not there will be an unusual amount of blow back with sized casings. Bullet selection, the charge, case sizing, and crimping are some of the considerations.

    Both gas cutting and blow back are a couple of things to think about.
     
  17. Oyeboten

    Oyeboten Member

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    Hi Clembert,


    I have a couple old Revolvers where regular .45 Colt was a little too small for the Cylinder Bores and Barrel...so, I fire formed some Cases for them, and then was able to thumb-press a .454 Bullet into the Cartridge case.


    Someday when I can finally get onto firing up my Metal Lathe I would like to make a set of re-loading Dies for managing these Cartridges.


    As it is I have been managing to do a good crimp using an old .45-70 Crimp Die...but am at a loss for re-sizing, which has not been a problem yet, but, one of the Revolvers is a little smaller in the Cylinder Bores, so now Cartridges which fit the more ample one, will not fit that one...so, being able to re-size for the smaller of the two would be nice.


    I am confident, that if you wanted to do so, you could ream or step-ream your Cylinder Bores a little larger, for the thence to be fire-formed .460 S&W Magnum Cartridge Cases, to hold and crimp a .454 or .455 Bullet.


    Obviously you are very skilled at Metal Working and Gunsmithing, so, I would expect you could also make some dedicated re-loading dies for this, which would sure be cool..!
     
  18. ClemBert

    ClemBert Member

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    Unfortunately, you couldn't be farther from the truth. I can't take credit where credit is deserved. I used the services of two different gunsmiths to complete this project. The names of these gunsmiths would be recognized by many folks on this forum. They have the expertise and the CNC equipment. I only get credit for seeing this project through.

    As for reloading dies there isn't anything special that is needed. I have Lee .460 S&W Magnum and .45 Colt reload dies. The beauty is that that's all there is needed to reload various cartridges for this Walker.
     
  19. Oyeboten

    Oyeboten Member

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    But .45 Colt or .460 Dies would not be able to re-size Cases for using .455 Bullets, is what I meant.


    That is the issue I am running into with my .45 Colt Revolvers which have generous Bores...and for which the usual .453 Bullets are too small.


    Really lovely project and the WALKER looks mighty good with those mods!
     
  20. ClemBert

    ClemBert Member

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    I guess I'm not understanding your reference to 0.455 diameter bullets. Perhaps you are just trying to figure out a solution for your old .45 Colt revolvers rather than wondering how I would get a 0.455 bullet into a .45 BPM.

    What I was trying to point out is that the Walker with a Kirst Konverter supposedly should be able to shoot .45 Colt cartridges with 0.452 diameter bullets without a problem. Because the Uberti Walker can be expected to have a groove diameter greater than 0.452 we need to rely on soft lead bullets to flare out under pressure from the burning BP. This, hopefully, will obturate the barrel and prevent gas cutting. Again, a 0.452 bullet is already 0.002 larger than a shaved round ball shot from the cap-n-ball cylinder. For this particular Walker I'm trying to understand the desire to use a 0.455 bullet although I will admit that with a larger bullet less reliance would be placed on flaring of the bullet.

    Technically, a 0.451 round ball in a cartridge also is larger than a shaved 0.450 round ball in the cap-n-ball cylinder chambers. 0.450 is the diameter of the chambers on this Walker's cap-n-ball cylinder. So....if a 0.454 round ball shaved down to 0.450 in the cap-n-ball cylinder works then logically a 0.451 unshaved "should" do the job. And, a 0.451 should easily slide into the casing.

    Now, regarding a 0.454 round ball in a cartridge...

    For the sake of discussion let us assume we want to load either a 0.454 round ball or a 0.454 bullet into the .460 S&W Magnum casing. To make this easier we can either use the flaring die of the .45 Colt die set to flare the case. This would allow a 0.454 projectile to squeeze in. Another route to take is to use brass that was already fired in this Walker and therefore expanded larger than an unfired casing. By skipping the resizing step that "shrinks" the case back down you would be working with a larger diameter casing. This in theory only as I do not have any fired cases. I can say that the chambers on the conversion cylinder are 0.482. If there is enough pressure built up to prevent blow back the cases will expand to 0.482. Likely they'll bounce back to a smaller diameter as the pressure dissipates. What the final diameter is is anyone's guess. I do know that resized brass takes it back down to 0.474 (external diameter).

    Likely, with the chamber diameters of 0.482, the fit will be so tight as to make the use of 0.454 conical bullet undesirable. However, with round balls there is actually very little surface contact (at 0.454) with the inside of the casing. Read this to mean that using 0.454 round balls is probably do-able although a very tight fit. Theoretically, if the walls of the casing are thicker than 0.014 then the math says its a no-go. The casings I've measure are right at about 0.014 in thickness. Ergo, a very tight fit!

    So where does one go to get 0.452 soft lead round balls?
     
    Last edited: Oct 13, 2010
  21. ClemBert

    ClemBert Member

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    Yes, it would seem that one could load two 0.451 round ball in a cartridge. I would assume that you'd have to be very careful to pack the area where the balls touch with a filler material. Without that packing you'd have an air gap between the balls. Sounds potentially risky. No? :confused:

    Discuss....
     
  22. junkman_01

    junkman_01 member

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  23. Oyeboten

    Oyeboten Member

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    Oh...yeah, I was thinking the WALKER Bore was a little large for a .452.
     
  24. ClemBert

    ClemBert Member

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    Thanks for the link junkman. Good read.

    From what I've seen posted of the Uberti made Walkers the bore is right near 0.440. Mine is 0.439-0.440.
     
  25. Pulp

    Pulp Member

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    I never have measured my R&D cylinder or the barrel bore, but mine shoots pretty darn good with .452 bullets. I was able to regularly hit a 16X16 inch steel plate at 100 yards with mine.
     
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