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Thread: Brennecke slug mold

  1. #1
    Boolit Master Cap'n Morgan's Avatar
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    Brennecke slug mold

    A couple of months ago I was on a wild boar hunt in the Czech Republic with a couple of friends. We had a great time and managed to bag few boars. The locals use shotgun slugs for a great part of their hunting, but unfortunately the quality slugs are quite expensive, so it is common practice to just swap the shot in an ordinary shell with a hollow lead slug - sort of a fat lead washer - and bang away.

    I tried a couple of shots with these makeshift slugs and wasn't impressed, to put it mildly. I decided I would design a mold which would cast a decent Brennecke clone - which they all agreed was the most accurate slug for smoothbore guns - and try to work up a load that could duplicate the Brennecke's performance.

    I have only little experience with slugs as they have been prohibited in Denmark for several decades, but lack of experience has never stopped me from doing stoopid things

    Before I started I decided on a few things: The diameter should be 0.728 and the weight 1-1/8 ounce. The slug must have some sort of "fins" to allow it to pass through a chocked barrel without damaging it, and it must have a hole for attaching one or more felt wads to achieve the shuttlecock effect. This is what I came up with :



    Basically the mold consists of two parts; A single part body and a "lid" - actually a sprue plate, that has a core on one side and a sprue on the other. The two parts locks together with three matching lugs. The mold is filled through three 2mm holes in the lid. Twisting the lid will open the mold and snap the sprue(s) at the same time -or so I hope.
    The reservoir has tapered sides and the sprue should drop freely when lightly tapped - again, so I hope!
    I added a spring-loaded plunger in the center of the body to ensure the slug can be ejected as the slug ribs has no taper.

    The mold(s) are almost finished. All I need is to make the center plunger and we're ready to roll. I'm crossing my fingers.





    Cap'n Morgan

  2. #2
    Boolit Master



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    Really nice work. Anything slug related interests me. Looking forward to your future posts on the progress and completion of this most worth endeavor.

  3. #3
    Boolit Master
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    You are wonderfully crazy.
    That looks incredibly tedious from a production standpoint but the tooling is beautiful, a work of art.
    I stand in awe, you have gone to astounding lengths to manufacture something to squirt accurately out the end of a shotgun barrel.
    I love this stuff and particularly what you have done.

    Can I ask the process of making the slugs, I can't quite picture how it's done given the images.

  4. #4
    Boolit Master

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    I made a simple push out mould that makes a finned or ribbed slug. The finned slug was similar to the Corbin swaged "bomb" slug. I found that keeping fins from distorting was difficult and required oven heat treating then wads became the issue as they would shred between fins! I decided to modify the mould to make a straight ribbed hollow base slug then fill with hot melt glue. That didn't go so well either. Now I am working on a Brenneke style as well.

    The biggest problem I have had is making consistent "skirts". What do you plan to use for yours?

    I have tried nitro card wads and other stacked materials screwed on but so far no success that way. The best results I have gotten are using hot melt glue cast on in a form. That works pretty well (poor man's injection moulding) but... you need to keep the glue from sticking to wads under firing pressures. I use wheelbearing grease as mould release in my form for the glue skirts but it leave the glue a bit soft on the surface. I add some grease before loading into wads and that seems to work reasonably well.

    I shot some today but had wad release issues. That hasn't been a problem in past testing but it bit me today! I tried a silicone spray on th eslugs this time. Bad idea! I am guessing the solvent attacked the glue. DOH!

    Anyway, I am rambling on here.

    Your mould looks really good! Nice work!

    I will be very interested to see your finished Brenneke clones and what you use for attached wad (I think that is the secret to success here!). Nylon, Delrin or some other plastic rod machined to diameter and screwed on would probably work but would be time consuming to make and not easy for the home caster at least if he doesn't have a lathe.

    I am thinking that Brenneke attach oversize wads then shear them to size with slug attached to get the consistency they do.

    From your graphics I am guessing your mould is base pour through the 3 holes with nose ejector rod?

    Mine is nose pour with a separate nose form that drops in under the sprue plate. I handle it with a magnet while casting.

    I will be following with interest.

    Longbow

  5. #5
    PAPERPATCH MASTER


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    I`ve never really heard a good answer as to why Brenneke slug ammo isn`t being brought into the U.S. anymore. Anybody ever hear why?Robert

  6. #6
    Boolit Master

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    I wonder the same thing though slugs are not that common where I am in Canada. Generally we can find full bore rifled Foster slugs but nothing like Brenneke or Gualandi.

    Is there no Brenneke slugs/ammo available at all in the US? There is a Brenneke USA website so it makes one wonder.

    I bought reloadable Brenneke slugs many years ago and they shot quite well for me. I also remember reading an article by Ross Seyfried on Brenneke slugs in the relatively early days of rifled shotgun barrels and the Brenneke technicians were questioning why Americans were going rifled barrel as the Brenneke slugs were apparently accurate enough for hunting to 100 yards or so. Of course rifled guns are now shooting very small groups so better than any smoothbore.

    There certainly is a better variety of slugs for smoothbores in Europe though and some pretty sophisticated designs too!

    Anyway, I like smoothbore with full bore slugs so I am hoping Cap'n Morgan is successful. he has certainly put together an impressive mould!

    Longbow

  7. #7
    Boolit Master Cap'n Morgan's Avatar
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    Longbow,

    I'm planning to use old style felt wads for skirt - sandwiched between a couple of nitro cards and attached with a self tapping screw. I will probably make some sort of fixture to assemble the slug & skirt to keep things aligned. Maybe also for pre-drilling the center of the wad if necessary. I guess the best way to load a slug is to use roll-crimp? A friend of mine has a large collection of antique loading tools - including 5/8" thick felt wads. He'll probably donate a crimper for the cause.

    Oldpara,

    Perhaps this cutaway is more informative. The cavity is filled through the reservoir in the green top-part and flows into the cavity via three small holes/inlets. Since the inlets are arranged off-center, twisting the top-part will snap them off where they attach to the slug:

    Cap'n Morgan

  8. #8
    Boolit Master TheDoctor's Avatar
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    Please keep us in the loop on how this works out. Might even be able to find buyers if you felt like making a few extra. Looks good, and Brennecke K.O. are my favorite.

  9. #9
    Boolit Master
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    Quote Originally Posted by Cap'n Morgan View Post
    Longbow,

    I'm planning to use old style felt wads for skirt - sandwiched between a couple of nitro cards and attached with a self tapping screw. I will probably make some sort of fixture to assemble the slug & skirt to keep things aligned. Maybe also for pre-drilling the center of the wad if necessary. I guess the best way to load a slug is to use roll-crimp? A friend of mine has a large collection of antique loading tools - including 5/8" thick felt wads. He'll probably donate a crimper for the cause.

    Oldpara,

    Perhaps this cutaway is more informative. The cavity is filled through the reservoir in the green top-part and flows into the cavity via three small holes/inlets. Since the inlets are arranged off-center, twisting the top-part will snap them off where they attach to the slug:


    The mold looks great !
    I hope it fills the cavity consistently without evacuation (vacum) or centrifugal force.
    Those are very small sprues.
    Again, nice work !

  10. #10
    Boolit Master

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    Cap'n Morgan:

    I have tried nitro card wads and they did not work for me. They tend to delaminate and get a but "messy" at firing. At least the ones I used did. Of course the recovered slugs don't tell the whole tale but shot into sand at 100 yards, I found the attached wads did not appear to have held together well and accuracy was poor.

    I suggest using plastic washers of some sort maybe punched out of polyethylene sheet. Alternately, heavy leather washers might work too.

    I have not tried felt as I could not get dense enough felt to try out. The only source I know of readily available would be felt wads from BPI or other shotgun reloading supplier.

    I made up a jig to assemble my Brennekes but even then I found things weren't perfect. I suspect that Brenneke assembles the wad components onto the slug then shears to slug size with a punch. The ones I have seen certainly look that way anyway.

    possibly 10 ga. felt wads could be assembled by punching or drilling a screw hole then attach to the slug, then run the assembled slug through a sharp punch to shear off anything larger than the slug.

    As mentioned, the best results I have had are using the hot melt glue cast onto the slug. in a form. They are pretty consistent and tough.

    In any case, I am rooting for you! I want a good smoothbore slug I can count on. So far the best I have shot are AQ slugs which turned in about 6" + a bit groups at 100 yards. If I could do that all the time with home made slugs I would be happy. I think of the AQ as a modernized Brenneke ~ same principle anyway. I think if I had Brenneke clone of factory quality to load they would do just fine.

    Go get 'em Cap'n!

    When are you casting and shooting?

    Longbow

  11. #11
    Boolit Master

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    I'm thinking the cap'n is just showing off! Not just the mold but the graphic representation. Nice work all the way around. Most impressive!
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  12. #12
    Boolit Master
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    Very impressive work. Hope you can post test results soon.

  13. #13
    Boolit Master Cap'n Morgan's Avatar
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    I'm thinking the cap'n is just showing off! Not just the mold but the graphic representation. Nice work all the way around. Most impressive!
    He,he, I know the graphic drawings may look a little over the top, but there's a meaning to the madness. The software I use (SolidWorks) takes the guesswork out of designing. All parts are constructed using parametric driven values. That means you can change (read: fiddle) with everything throughout the design process. Would you like to increase the number of ribs from 8 to 10? Just change a single number and the change is made. What will the final slug weigh? Just set the material to "pure lead" and let the program do it's thing. Too heavy? Change the value for the length and the weight will change accordingly. It's like having an infinite number of prototypes at your disposal.

    The best part, however, is that once you have the design you want, you can export the part to a CAM program and machine the part directly from the graphic representation - also called a "solid". Just point at the surfaces you want to machine, choose an appropriate cutter, and press the green button. Well... there's a little more to it, but not much.

    As a bonus, making drawings and cut-away inserts like the ones I posted is as easy as pie.
    Cap'n Morgan

  14. #14
    Boolit Master

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    Cap'n:

    You mention ribs. One of the things I found with my Brenneke was that I used 6 ribs and they got smushed! I made a long bodied Brenneke with a long wad column and hefty screw to hold it all together and recovered slugs showed that the ribs did not have enough area to support the slug and so they collapsed diagonally (leading edge at nose and trailing edge opposite side on base). I think "too much" rib is better than too little rib. then I went to a shorter Brenneke with wider ribs, still no go!

    Photos attached: Click image for larger version. 

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    Make 'em beefy and not fragile is the moral of the story!

    Wishing you success! Go get 'em Cap'n Morgan!

    Longbow

  15. #15
    Boolit Master

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    Quote Originally Posted by Hardcast416taylor View Post
    I`ve never really heard a good answer as to why Brenneke slug ammo isn`t being brought into the U.S. anymore. Anybody ever hear why?Robert
    I still see it around at shows. And online.

    http://www.ammunitiontogo.com/index....acturers_id=37

    http://www.ableammo.com/catalog/bren...517_15439.html

    http://www.cabelas.com/shotgun-ammun...un-slugs.shtml

  16. #16
    Tagged for updates. This is a sexy mold.

  17. #17
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    Wow! that's impressive.

    instead of HOT lead I would have just looked at makeing a swaging mould, and swaged them
    Sometimes you have to ignore the "good idea fairy"

    Please stop telling me "That can't be done" while I'm doing it, it's just plain annoying.

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  18. #18
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    Heres a disection of an original Rottweil Brenneke slug.







    Dimensions



    It is swaged from dead soft lead.

    I do believe that the finns being askew has a big impact on stability in that it will induce rotation to some extent during flight.

  19. #19
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    Well curiosity got the better of me and i whipped out this MK I swage die.

    From left: 450gr .515" donor, result from press, result from hammering and original.
    It's a smidgen short because it is solid for the weight. I need a brewsky or two and thenn i'll do something in order to get the "cavity".






    Newsflash: Brass it no good for swaging dies! Man did i have a fight to get things dissassembled after the 6 ton press had done it's work.

  20. #20
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    MK II is up.

    I added cavity for the bottom rim and hole for the screw.








    Goes to show that it is possible but not easy to get a good boolit.
    I will do some shots for this sundat and report back regarding accuracy

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check