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Breech Plugs for Break Action Inlines Using Cartridges

Discussion in 'Blackpowder' started by Snidely70431, Jan 31, 2019.

  1. Snidely70431

    Snidely70431 Member

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    My experimentation with breech plugs for break action inline muzzleloaders using cartridges was triggered by articles about conversions of factory breech plugs to use .25 ACP cartridges or Variflame adapters in place of #209 shotgun primers, on the theory that less powerful primers give better accuracy.

    My reasoning was that, if one were to use a primed cartridge case to set off a muzzle loader charge, why alter a factory breech plug to accept a cartridge case? Why not build a breech plug around a cartridge case from scratch? To answer the objections of so-called traditionalists, Harry Pope was building rifles this way in the late 1800's.

    upload_2019-1-31_4-16-32.jpeg

    To this end, I began examining the factory plugs. I found that CVA break actions, both the older recessed breech plugs and the newer Quick Release types, and Rossi Muzzle Loaders, all use a breech plug with a 5/8 - 18 basis. Searching on line I found that Home Depot sells a line of Crown Bolts, Grade 8, that are 5/8", 18 threads per inch.

    upload_2019-1-31_4-23-27.jpeg

    So far, I have built proof-of-concept breech plugs for both the older and newer CVA's and the Rossi, in .32 ACP, .38 Special, 9mm Luger and 5.56 NATO (cut off to 1') primed cases, and they have all functioned well with loose Black MZ.

    I will be posting pictures of my breech plugs when I get around to taking some, and providing information about ballistics as I assemble it. :) Right now, I am at the "well, it does go BANG!" stage.
     
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  2. arcticap

    arcticap Member

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    That sounds very innovative and I'm really looking forward to seeing the details.
     
  3. Snidely70431

    Snidely70431 Member

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    Sorry about the lack of quality of the pictures, but I used what I could find as a digital camera. It's really a cheap video camera.

    Explanation about why I used the Grade 8 crown bolts, besides being cheap, fast and easy in comparison to cutting threads:

    Grade 8 Bolts and fasteners are comprised of carbon-alloy steel, heat treated in a carbon controlled atmosphere and are generally the most durable and reliable fastener. Grade 8 bolts have the highest ratings with tensile strength of 150,000 psi. Grade 8 bolts are used marine, military, aerospace, off-road vehicle markets and related mechanical applications where stress and strong load bearing pressure is required.

    upload_2019-1-31_18-0-44.jpeg

    These are different versions of breech plugs for the CVA V2 line of break action inline muzzle loaders. The one on the left is just a threaded piece cut to size and drilled for a cartridge case. To this was added a 5/8-18 nut purchased off of EBay and thinned a bit to fit in the V2 gap, total cost of materials about $3.

    The two versions on the right are made from just a bolt. This is an easier job, but the finished product does not look as good, there being a gap between the barrel and the bolt head in which the thread can be seen, but it seems to work as well. :) It did not blow up.

    upload_2019-1-31_18-27-44.jpeg

    The top and right breech plug in this merged picture is made to fit the CVA V1 muzzle loaders. The shorter breech plug is made to fit the Rossi muzzle loader. Since I wanted the breech end of the breech plug to be in direct contact with the receiver I did not allow for a hex nut for unscrewing the breech plug. Instead, I used a Dremel cutoff wheel to make a small cut in the face of the breech plug across the chamber. A piece of hacksaw blade end fits in this and I have had no trouble unscrewing the plug, and the fired cases show no sign that this is a problem.

    I'll try to find my better digital cameras and post some better pictures, along with more information as I develop it.
     
    Last edited: Feb 1, 2019
  4. Snidely70431

    Snidely70431 Member

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    As promised, better pictures:
    upload_2019-2-2_6-24-2.jpeg

    These are the breech plugs made for the CVA V2 line of break actions. The one at the top takes a .38 Special cartridge, the one in the middle a .223/5.56 cartridge shortened to 1", and the bottom a 9mm Luger.

    upload_2019-2-2_6-28-37.jpeg

    The shorter of the breech plugs is made for the Rossi, the longer for the CVA line of break actions that preceded the V2 line with quick release breech plugs. The piece of hacksaw blade functions as a wrench to unscrew these breech plugs. The CVA plug is chambered for a 38 Special, the Rossi for a .223/5.56 shortened to 3/4 inch.
     
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  5. arcticap

    arcticap Member

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    What is the diameter and length of the flash channel, or is the cartridge diameter drilled completely through the length of the bolt/breech plug?

    Is the length of the flash channel different for every cartridge case?
    Is the loaded powder flowing directly into the case?
     
  6. arcticap

    arcticap Member

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    Some folks adapt their breech plugs to use replaceable vent liners that are based on using Savage vent liners.
    But some individuals are able to make their own replaceable vent liners by using a drill press to drill a hole in a small hard screw which can be swapped out if the flash channel becomes eroded and too large.
    Badger even offers a .036 pin gauge to measure if the amount of erosion of the vent hole becomes excessive over time.

    Here's some Lehigh vent liners which are supposed to be super hardened.
    The 1st link has highly detailed photos:

    1. https://www.badgerridgeind.com/store/p11/LehighVentLiner.html

    2. https://www.lehighbullets.com/product/vent-liner-for-savage-mlii-and-all-lehigh-breech-plugs/

    The maker of Vari-flame makes the Savage vent liner flash channel to their own dimensions.--->>> https://www.prbullet.com/vl.htm
     
    Last edited: Feb 2, 2019
  7. Snidely70431

    Snidely70431 Member

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    A 38 Special cartridge is a 38 Special cartridge. A 9MM cartridge is a 9MM cartridge. A 32 ACP cartridge is a 32 ACP cartridge. A .223/5.56 cartridge is modified as to length, either .750" or 1.00" long, so that the bottleneck is removed.

    The rim of the 38 Special contacts the receiver and the breech plug, the powder comes down the barrel and into the cartridge and up into the barrel; there is no "flash channel" per se, just an opening above the cartridge case. The 32 ACP, while ostensibly rimless, has enough of a rim to prevent the case being pushed into the chamber.

    The 9MM and .223 breech plugs are drilled through, I think .350 and .320, respectively, then a chamber is drilled between the face of the breech plug and the muzzle end of the breech plug, just deep enough that the front of the cartridge case prevents the cartridge case from being forced into the breech plug by the firing pin.

    All of this is just as it is in a normal firearm. The difference is the breech plug is screwed into the barrel, the case is put in the chamber in the breech plug, the powder is put in the barrel muzzle, then the projectile is seated on top of the powder. When the rifle is fired, the cartridge case seals the back.

    Modern 38 Special cartridges are speced at 18,000 - 20,000 PSI, 9MM Luger cartridges at 35,000 PSI, 32 ACP at 20,500 - 23,000 PSI and 5.56 NATO cartridges at 55,000 - 62,000 PSI (This is probably why the .223/5.56 case allowed some blowback around the case. There may not have been enough pressure to completely seal the case in the chamber.)
     
  8. Snidely70431

    Snidely70431 Member

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    Every time a primed case is put in the breech plug it is as if a new vent liner was put in. In effect, you are handloading each round. You put the primed case in the breech plug, then the powder into the muzzle, then the projectile on top of the powder.
     
  9. Snidely70431

    Snidely70431 Member

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    upload_2019-2-2_18-23-57.jpeg

    This is a picture of the 38 Special breech Plug for the CVA V2 variations.
     

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  10. Snidely70431

    Snidely70431 Member

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    upload_2019-2-2_18-32-42.jpeg

    This is a picture of the 9MM breech plug for the CVA V2 variations.
     
  11. arcticap

    arcticap Member

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    Thanks for the answers to my questions.
    I realize now that I should have used the words cartridge case, and not cartridge when referring to the brass cases.

    One of the reasons that I had mentioned the vent liners is because I think that the maker of the Vari-flame seems to infer that
    their breech plug kits may have some form of small vent hole or flash channel in their breech plug.

    They say over and over how too much primer flame from 209's does not make it through the small vent hole which causes problems.
    I don't know whether they have totally eliminated the breech plug vent hole or not, but I didn't think that they eliminated it.

    Do you know if they eliminated it or not as you have up to this point?
    I suppose that I could ask on another forum in an effort to locate an actual Vari-flame user.
    But if they haven't eliminated the vent hole and they have eliminated flyers for the most part, and you don't have a flash channel,
    then the next question would be, does your breech plug system also eliminate flyers?
    I suppose that it may be too early to tell, since a lot of accuracy testing would need to be done.
    And I also realize that eliminating flyers may not be your goal.

    Whether your breech plug system does eliminate flyers or not, it's still a worthy effort since 209's have their problems.
    But if you were trying to eliminate flyers and have gone through this effort and have not, then you may want to consider
    the next step.

    At the very least, building a flash channel into your plug might eliminate some blow-back and pressure in the brass cases.
    But it would introduce another problem of keeping the flash hole clean.
    Many folks use a small drill bit to accomplish that.

    I also wonder if you can safely ignite Black horn 209 powder or not using smaller primers.

    I've read more than several pages on the Vari-flame maker's website, and he doesn't actually state if his plug is designed with or without the vent hole.
    But as I read it, he seems to infer that he might have kept it in his design.
    But I don't really know.
    Do you?
    In the meantime, I will consider trying to research if the Vari-flame has a small vent hole or not.

    BTW, one last question that I have is what kind of primers are you using?
     
    Last edited: Feb 2, 2019
  12. arcticap

    arcticap Member

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    Also, how can you be sure that your brass cases are being completely filled with powder and not have any air gap when loading powder?
    Any chance of powder hang-ups?
    A flash channel or vent liner could eliminate that possibility.
     
  13. arcticap

    arcticap Member

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  14. Snidely70431

    Snidely70431 Member

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    The 9MM cases were primed when I bought them at a gun show. I replaced the .32 ACP and the 38 Special primers with small pistol primers. I replaced the .223/5.56 NATO primers with small rifle primers. I do not remember the brands.
     
  15. Snidely70431

    Snidely70431 Member

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    The largest capacity case I am using is the 38 Special. Wikipedia gives the cartridge case capacity as 23.4 grains of water. I have read elsewhere that water and black powder have about the weight per volume, so any reasonable volume of powder or powder substitutes would more than fill any of the cases. Any excess would be in the barrel, just as it is with commercial breech plugs.
     
  16. Snidely70431

    Snidely70431 Member

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    I am not anywhere near testing my breech plugs for accuracy, or even consistent velocity. I want to try some other cartridge cases.
     
  17. WestKentucky

    WestKentucky Member

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    It would be nice if you could set your cartridges up as paper or cardstock capped blanks. Perhaps a 44 mag case or something similar of appropriate size to hold the right volume of powder, and then have a larger diameter barrel in front of that upon which you could seat your bullet. I really like this thought as it allows for easy unload if you don't shoot and want to unload. You can easily check for bullet with a flashlight, and you can easily verify unloaded for transport. I am thinking about a fat case in the 50 caliber range where a pellet could be used, but the rifle would have to be a 54 or larger to prevent your front stuffer to be stuffed from the rear.
     
  18. Snidely70431

    Snidely70431 Member

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    Even a 44 Magnum has a case capacity of only 37.9 grains of water (Wikipedia).

    I tried to find out the diameter of .50/50 pellets and one forum post lists them as .454", so they would not be usable with my cartridge case breech plugs.
     
  19. arcticap

    arcticap Member

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  20. Snidely70431

    Snidely70431 Member

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    The only blowback I experienced was when using a shortened .223/5.56 case. I think the pressures were just too low to expand the strong case to fit the chamber. All the other cases had no blowback at all.

    As for primers, I mostly used small rifle primers in the .223/5.56, small pistol primers in the .32 ACP, 9mm, and 38 Special cases, and a large pistol primer in the 45 Colt. As a test, I used a small rifle primer in a 38 special case and it worked just fine. I had no ignition problems at all with any powders.
     
  21. Snidely70431

    Snidely70431 Member

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    I have been playing with different cartridges for my breech plugs (BP), and tried .25 ACP, which is a PITA, because the cartridge dimensions are all wrong for the reamers I have and it is too small to be pushed out of the BP with a .25 brass rod.
    The most successful cartridges I've tried for the Rossi break action BP's (5/8 -18 thread) are the 9MM Luger cartridge, which is .75" long, and the .32 ACP cartridge, which is a little shorter but has enough of a rim that it head spaces on the rim. The .38 S&W would probably work but I do not have any brass to try with it.
    The CVA break actions BP's, both the older Optimas, etc, and newer V2's, are both 5/8-18 threads. These BP's are longer and there are more cartridges that work with them. Besides the 9MM and .32 ACP, I have made BP's using .38 Specials, .45 Colts and .32 H&R Magnums. Haven't had any problems with any of the cartridges.
    I gave up on using the shortened .223/ 5.56 cartridges. They are built to withstand pressures in the 55,00 - 62,000 psi range, and they do not seem to expand enough to seal the chamber and I have been getting some blow by.
    If anyone else on this forum has tried using breech plugs with cartridges, I would be interested in hearing about them.
     
  22. Snidely70431

    Snidely70431 Member

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    Latest build, a breech plug for a Rossi .50 ML that uses a primed 9MM cases.

    upload_2019-5-5_21-0-56.jpeg

    The bolt is like the one from which the breech plug is fabricated. The object on the right is used to hold the breech plug in the lathe so the jaws don't contact the threads. I tested the breech plug by discharging 3 each 50 grain Pyrodex pellets topped by a 14.4 grain TC #170088252 Sabot and a 300 grain Speer .451 jacketed soft point 45 Colt bullet.

    Test was successful. Threads sealed, case intact, propellant discharged properly.

    The object center bottom is the wrench used to screw the breech plug in and out. I fabricate them out of steel banding material. The horns fit into the indentations on the breech plug.
     

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    Last edited: May 5, 2019
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  23. gemihur

    gemihur Member

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    Is all this really necessary?
    Did not your firearm have an effective ignition system already?
    Does your breech plug modification and case ignition offer improvements to either 209 or #11 caps?
    I'm not inclined to complicate a process unless it results in measurable gain in either accuracy or velocity.
    I too appreciate the theories of Harry Pope and his barrel making techniques.
    I'm intrigued in the concept but apprehensive to embark on a fruitless endeavor.
    Thanks for your great descriptions of the modifications you've done.
    I am eager to see your work's outcome.
     
  24. arcticap

    arcticap Member

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    Snidely70431 is making his own versions of the .25 acp conversion and Variflame large rifle priming adapter system that was invented by the owner of a Canadian outfit named PRBullets.
    It was shown that primers smaller than the 209's in current use promoted better accuracy and consistency.
    And now CVA has built their newest top of the line muzzle loader named the Paramount using the same Variflame primer adapter from PRBullets.--->>> https://www.muzzle-loaders.com/cva-paramount-muzzleloader-rifle-pr3501n.html
    Can't blame a guy for trying to improvise and build his own conversion breech plugs in an effort to obtain similar results, while also being able to use a greater variety of primed brass cartridges.
    Quite innovative and a rewarding hobby sort of like making black powder from scratch.
    Of course PRBullets also sells premium bullets to help maximize accuracy.

    Here's the PRbullet .25 acp conversion:--->>> https://www.prbullet.com/prohntr.htm
    The PRBullet home page for more product info.:--->>> https://www.prbullet.com
    Variflame info :--->>> https://www.prbullet.com/vf.htm &--->>> https://www.prbullet.com/lrvf.htm
     
    Last edited: May 13, 2019
  25. Snidely70431

    Snidely70431 Member

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    I'm a retired person who enjoys tinkering with things. I buy muzzle loaders cheap - almost always under $100, sometimes as little as $60 - mostly at pawn shops but also at gun shows. Since Louisiana's "primitive weapons" season for deer now allows a single shot .35 Whelan, any single shot 35 caliber or better, muzzleloaders are a drug on the market. Plus, I don't hunt.

    I like playing with smokeless loads, mostly Unique, that are less powerful than recommended BP or BP substitute loads in my rifles. Cartridge case breech plugs work much better for this than 209 or #11 ignition, although I also test my breech plugs with Pyrodex pellets at the recommended maximums as a precaution. I have never had a failure.
     
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