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Thread: Brenneke slugs - light at the end of the tunnel...

  1. #1
    Boolit Master Cap'n Morgan's Avatar
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    Brenneke slugs - light at the end of the tunnel...

    I had the Brenneke slug project on the back burner for quite some time now, but finally most of the kinks has been straightened out.

    Here is the three different stages of design with the original Brenneke to the right. The final design ended up quite similar to #2, but with a little different nose shape - and since the wads and slugs are now glued together I did away with the screw hole in the base, which allowed for a larger sprue hole.



    A picture of the latest design. The helical fins was something of a headache to program for in the EDM sinker, but they came out quite well:



    I ran out of epoxy for the wad mold so, being a cheapskate, I switched to polyester resin instead. Unfortunately the difference in shrinkage meant a new wad mold had to be made:



    This is what the finished combination looks like. The combined weight is close to 1-1/4 ounce (540 grains) with the wad weighing 60 grains.
    (notice how a few hours in the sun has bleached the yellow/green color to a grey hue)



    And finally the end result... Loaded shells! I came across a batch of old 2-1/2" paper hulls with gevelot primers. Loaded with 30 grains Herco and a 3/8 felt wad under the slug they are just the right length for a nice roll crimp. The speed is 1250 fps.



    I have only done a little testing with the slugs so far and while the results are as good or better than the previous design, there are still room for improvement. At fifty yards the groups are 4-5" on average and a five shot group at 100 yards gave a decent 12" group, but still a far cry from the 3-4" groups George Vitt claimed from his Vitt slugs. So far I have only used a gun with modified choke (0.02 constriction) a cylinder- or improved cylinder bore will probably produce better results. Next project will be adding a holosight to my skeet gun for testing. I'm also on the lookout for a cheap single barrel gun which would be perfect for scope mounting.

    At this time in the project I must admit it has mostly become a fun hobby. The original goal was a slug for my Czech friends to kill running hogs at distances from zero to forty yards - and the slug will easily accomplish that. Now it is more a question on how much accuracy you can wringe from a smoothbore shotgun barrel. Only time will tell.
    Cap'n Morgan

  2. #2
    Boolit Master
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    Very nice looking slugs... you have enormously more patience and skill than I possess! I happy just to cast Lyman 525's and fill base with hot melt.... you take slug making to a new level... congratulations... hope the testing works out well for you.
    Perhaps my learning skills have diminished in my senior years.. 50 years ago I could read something once and then "have it"... Now I read it about three times, do it a couple of times and then... "have it" only about half the time.

  3. #3
    Boolit Grand Master

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    Very nice Cap'n Morgan! Beautiful job on the mold and slugs.

    Not sure how much difference the choke will make but I have to think that the more choke beyond size for size will cause inaccuracy ~ just my opinion.

    My Brenneke mould turns out much the same slug as yours except I do not have helical ribs. Personally I do not think helical ribs matter as it has been supposedly proven that Brenneke slugs do not pick up a spin from air drag. I think slug fit to bore, enough rib to center the slug without crushing and tipping (had that and photos to prove it!), wad alignment and absolute consistency are what matter.

    With your cast wads glued in place you should be right there with wad alignment and consistency. Those look very nice indeed.

    Do you align wads in a jig when you glue them on?

    Is that polyester resin hard or does it have some flex to it?

    What is you slug/wad fit to bore ~ clearance, size for size or interference?

    My last attempt with a Brenneke style slug was to achieve a slide fit of maybe 0.001" clearance as Ross Seyfreid said he found worked in an original Paradox gun but of course that that a choke rifled muzzle which squeezed the slug down. In any case, his description of the fit is that there was only enough clearance (maybe 0.001") that the slug would slip down the bore to the rifled choke. Not sure that applies to smoothbore.

    In any case, I have shot AQ slugs (very Brenneke like) that gave 6" groups at 100 yards so I know it can be done and that is good enough for me though the elusive 4" to 5" groups at 100 yards would be the prize. I certainly have not made it there but it looks like you have a good chance with those slugs. They are very, very nice.

    I still have slugs to test in my smoothbore but have abandoned smoothbore for now and am working on the rifled choke tube. Of course I am trying to replicate Paradox gun results but I hope you are successful with your slugs because my preference is to use smoothbore. I just haven't been successful enough at 100 yards.

    Good luck and I hope you are successful. Keep your eyes on the light at the end of the tunnel!

    Longbow

  4. #4
    Boolit Master AlaskanGuy's Avatar
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    Man, them slugs look awesome.... I want some......

  5. #5
    Boolit Master Cap'n Morgan's Avatar
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    Longbow.

    No doubt about it; wad/slug alignment is crucial to accuracy.

    The polyester resin wad has a tapered boss that match the core of the slug exactly. Still, I have contemplated some sort of jig
    (a tube perhaps) for even better alignment. The wads are pretty hard, which is why I added the ribs - not sure if a solid wad
    could damage the choke, but better safe than sorry.

    The slug and wad are both made oversize (0.729) compared to normal European bore size (0.724) The slug are 0.725 at the front, tapering
    to 0.729 at the base. I believe a tight fit is of outmost importance with these type of slugs.

    I may try an improved wad design with a hollow base with ribs - a bit like the old Alcan Airwedge. This would bring the weight down and move the center of mass a little forward. But first I'll need to try a more open choked gun. Stay tuned for a follow-up...
    Cap'n Morgan

  6. #6
    Boolit Mold vitralist's Avatar
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    Excellent Work Cap'n Morgan.

  7. #7
    Boolit Grand Master

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    0.724" certainly is tight. My slug guns run right around 0.729"/0.730".

    I agree 100%, a good tight fit is best, at least size for size and probably better at 0.001" or more over bore diameter.

    Is the polyester resin typical fiberglass resin? If so have you tried or thought of a hardish urethane? Some of the harder resins are sort of nylon like in feel and hardness. That might leave enough flexibility to obturate, harness to slip down the bore and flexibility to squeeze through at least a slight choke. There are likely others too. I am a bit familiar with some of the harder urethanes and they may be suitable.

    Yes, excellent work and I do hope you are successful! Well, more successful I should say because so far you are doing well. It is the elusive 4" to 6" groups at 100 meters we want to achieve.

    Keep up the good work and keep us posted.

    Longbow

  8. #8
    Boolit Master Cap'n Morgan's Avatar
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    Update...

    I finally got around to put a scope on my old Browning skeet gun and now has a true cylinder gun for testing the slugs. The scope is an old Leupold 2x handgun scope, but I don't mind a long eye relief when shooting 550 grains slugs for groups At first I tried a Doctor holosight, but had troubles focusing on the 3.5 MOA red dot at longer ranges.

    After attaching wads to some fifty slugs, I sorted them by weight in 0.1 gram increments (1.55 grain) It produced a crude Bell curve with the majority of the slugs placing in the 35.7 grams (551 grains) bracket, I then loaded 15 rounds of which five of the slugs came from the heaviest group, as they should be the most uniform of the lot.

    The load is as follows: 37 grains Blue Dot in a 2.5" paper hull with a slug/wad of 550 grains over a 27 grains felt wad - roll crimp.

    My plan was to shoot three groups at 25, 50 & 100 yards - five shoots each. This should give an indication of whether the spread would be linear or increasing with some factor over distance. Theoretical the spread should be non-linear until the helical fins has done their work - after which the spread should be pretty much linear (or so I hope). Unfortunately there was too much wind to make a reliable 100 yards test. The wind also meant I couldn't rig up the chronograph to test for speed (a 35 grains BD load gave 1150 fps) In the end I decided to go for the fifty yard group and then try at twenty five.

    I had only eyeballed the scope/bore and the first shoot landed about five inches to the right of the aiming point. Instead of adjusting the scope I decided to shoot the next four rounds, hoping they would stay inside the target. As you can see they DID stay on target. The nice three shot 2.5" group below is actually five shots - two of the holes are double hits! I must admit I was pretty pleased with the result. The distance was exactly 52 yards and I was leaning over the roof of my car for a good, steady hold.

    By now my right shoulder was starting to hurt, not because of the recoil as much as a severe case of "frozen shoulder" which has been buggin' me for several months now. Anyway, being a sissy I decided to leave well alone and try for the last two groups another day.




    If the spread is really linear at this range, it would indicate a possible five inch group at a hundred yards. It is probably too much to hope for, but anything less than ten inches will rate as a success in my book.

    Stay tuned for the final hundred yard chapter
    Cap'n Morgan

  9. #9
    Boolit Master

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    Outstanding Cap'n! You deserve a promotionin in rank: would Major or Commander be approriate? One question - what kind of gas seal do you use? Surely something under the felt wad?

  10. #10
    Boolit Grand Master

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    Looking good Cap'n Morgan! Excellent results. I will be looking forward to the next field report.

    I have to ask though... just where in Denmark do you lean over the roof of a car and shoot slugs!?! You sound like a local redneck. I always thought Denmark was more civilized.

    Longbow

  11. #11
    Boolit Buddy
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    They look really good. I'd love to get my hands on a few hundred of them

  12. #12
    Boolit Master Cap'n Morgan's Avatar
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    Hogtamer.

    The felt wad is 1/2" thick and it seems to do the trick, but gets a pretty good shredding in the process. The polyester wads base is about .01 oversize and no doubt makes for a good seal (and lead remover) once it enters the bore. I have some 1/4" plastic seals which I tried in combination with a previous design. The slug, wad and seal was glued together, but recovered slugs showed the seal lip (did I just write 'seal lip'?) would strip from the pressure. I may try to replace the felt wad with two loose plastic seals (the weight is almost the same) and then compare them over the chronograph, the fastest load would indicate the best seal.

    Longbow.

    I do most at my slug testing at a local farm. I help the owner culling foxes and get to do some shooting in return. This is great as there are not many places in Denmark where you can practice at 800 meters - of course, most of the year there will be crops in most of the fields, but you can always find a 200 m range somewhere.
    Cap'n Morgan

  13. #13
    Boolit Buddy
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    Time for me to be Captain Obvious, Those look so good, are you going to sell molds after you are satisfied with the prototype? I'm in if the price is halfway reasonable.

  14. #14
    Boolit Grand Master

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    Yes, that does sound pretty good. I am guessing you are not shooting slugs at 800 yards though.

    Where in Denmark are you? And where is the farm, nearby or long drive? Just curious.

    I'm lucky in the sense that I can normally be at the range in 40 minutes or out in the bush in 15 or 20 minutes. I live in a small town with not a lot around. The nearest "large" city is Kelowna about 3 hours away.

    While one would think there are lots of shooting opportunities, not so anymore. Pretty much anywhere you can drive in an hour or so there are quads, dirt bikes and mountain bikes where we used to shoot. I used to be able to drive for about 15 minutes to test loads out but mostly I go the the range now. Hah! I haven't even gotten out there to test my latest slug loads. Unfortunately too many things going on.

    Anyway, I digress.

    It is good to see you are making progress and it looks like good progress too.

    Maybe I should revisit my Brenneke design and work on wads. I think that is my weak link. Your success is making me want to get back at it.

    Keep up the good work!

    Longbow

  15. #15
    Boolit Buddy
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    Quote Originally Posted by schutzen View Post
    Time for me to be Captain Obvious, Those look so good, are you going to sell molds after you are satisfied with the prototype? I'm in if the price is halfway reasonable.
    id be in for one too

  16. #16
    Boolit Master Cap'n Morgan's Avatar
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    Longbow.

    The farm is less than half an hour drive away. If necessary I can also visit the local shotgun range fifteen minutes from here, but only for short range / chronograph testing and it's only open two days/week.

    If this project has taught me just one thing it is that the wad is more important to accuracy than the slug itself. My first slugs with machined solid wads shot great, but when I tried to cut corners using felt- or paper mache wads, precision would deteriorate as fast as the wads Using molded wads eliminated the problem - and at the same time did away with the need for a screw to hold the slug together.

    As for making Brenneke molds commercially, I'm afraid it is out of the question - at least for the helical version. There's simply too much work involved that I could keep the price down to an acceptable level. Sorry...
    Cap'n Morgan

  17. #17
    Boolit Master Cap'n Morgan's Avatar
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    Long time, no see...

    Another long due update in the never ending Brenneke story...

    Last time I posted I was all set to go for a hundred yard test. Unfortunately my frozen shoulder was getting progressively worse, but I thought I at least could manage to shoot five shots at 25 yards to chrony the load and then go for the hundred. Well, not quite... I managed one shot and then found myself moaning in intense agony as someone took an ice pick to my poor shoulder I finished the last four rounds from the left shoulder and managed a decent group (left in the picture) but when you're not a southpaw it's not funny shooting a load with a recoil in the 300 Win mag class. The speed was an even 1250 fps.

    After that experience I wasn't to keen on shooting anymore slugs. Shooting skeet with 7/8 ounce loads was still possible once you got past the first two stations and the shoulder had become sufficiently numb, but the slug shooting had somehow lost its attraction

    A couple of weeks ago I finally decided to try the slugs again. Wearing a padded shooting west and a Past Recoil Shield under my heaviest hunting jacket the recoil was nowhere as painful as I had feared and the slugs could at last be tested at 100 yards.
    The first round landed very close to the point of aim, but I believe I somehow blew the group by firing the next shot to soon after the first (the topmost in the middle group in the picture) The thin barrels heat up very quickly and since I was shooting the lower barrel on my o/u the POI could very well have moved up. For the last three shot the barrels was allowed to cool in between. The group measured exactly nine inches, but would have been seven inches if not for that second shot.






    On closer examination the holes in the target shows clear signs that the slugs are not quite stable, but have some wobbling or 'fishtailing' judging from the oblong holes. If one compare the 25 yards group with the 100 yards, it's clear that the holes 25 (and 50) yards group are perfect round compared to the 100 yard target. I suspect the resin wad, which are twice as heavy as an original Brenneke wad, are more prone to become unstable during flight. I will try machining a hollow base in a few wad and test again







    Still, I'm quite pleased with the results so far. The fifty yards group was shot using carefully selected slugs, but the other two groups had some less-than-perfect cast slugs in the mix. A more strict selection and perhaps a slightly modified wad and using some sort of fixture when gluing wad and slug together will further improve precision.

    Well, that's all folks. In a couple of weeks I should be in for an operation to fix my shoulder. It means no shooting for a month (and in the middle of the season, no less ) but right now I will gladly trade that for being able to sleep through a whole night undisturbed.
    Cap'n Morgan

  18. #18
    Boolit Master

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    Thanks for the update and best wishes for a successful surgery and complete recovery. Hal

  19. #19
    Boolit Grand Master

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    Looks pretty good to me. At least one of us is getting somewhere! I have not restarted my work on the rifled choke tube yet due largely to "life" getting in the way. I will get back to it though.

    I am still hoping you get these Brennekes tuned right up and it looks like you are on the right track. Personally, I still prefer the idea of a smoothbore than rifled barrel or rifled choke tube. I had given up on smoothbore though and figured the rifled choke tube might be the answer.

    You are giving me new hope for smoothbore accuracy and I am glad to see it. My original goal was a side by hammer gun with rifle sights and decent accuracy to 100 yards. Maybe a bit of a tall order being both smoothbore and side by but a guy can dream can't he?

    Best wishes on a successful surgery and outcome for your shoulder.

    Take care.

    Longbow

  20. #20
    In Remembrance

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    maybe the tail of one of these gizmos could be riggef into a good tail for your project:

    http://www.ballisticproducts.com/Sta...ctinfo/PEG12G/
    ____________
    "...the civil libertarians and rationalists who are ever on the alert to oppose tyranny "failed to take into account man's almost infinite appetite for distractions." In 1984, Orwell added, people are controlled by inflicting pain. In Brave New World, they are controlled by inflicting pleasure. In short, Orwell feared that what we fear will ruin us. Huxley feared that what we desire will ruin us. This book is about the possibility that Huxley, not Orwell, was right.” -N.Postman

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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