Longbow, I only told Cap'n Morgan his work was "some of the most promising work on shotgun slugs I have seen in a long time." Even Alexander Graham Bell, whom a benevolent Providence caused to be born Scottish, arrived in the patent office hours ahead of the competition, and mightn't have achieved as much without the effort being collective.
BiS.
I doubt the value of long forcing cones (and over-bore barrels) as well, but then again, I am allergic to hype under any form...
I did consider making a wad for a round ball at some point. Longbow and others have good results with those. At one time I made a simple compression mold for a paper mache wad for my Brenneke slug. The wad was a total failure, but it would be easy to make a non-attached, self-sealing, bio-degradable, cheapscate wad with a hemispherical impression using a simple mold and a loading press.
I may have to make a change to the short wad. Normally I glue the slug & wad together with a two-component adhesive, but polypropylene is reluctant to bind to anything. I have to try some different sorts of adhesive, but if not succesful I will modify the core of the mold to accept a small self-tapping screw just to make sure.
The slug for the long wad is finished. I had a couple of mold blanks lying around so it was quickly done. The fit between wad and slug is tight and I don't think there'll be any problems with the wad separating from the slug. I contemplated making a snap-lock in the wad, but it would call fore a more complicated injection mold.
Cap'n Morgan
It has become so original that you could about leave Brenneke out of it. In a rifled bore I doubt if that self-tapping screw could keep its mass central enough for the best accuracy, but its effect should be much less in a smoothbore.
Cap'n Morgan:
With your moulded attached wads and those beautiful slugs I am betting that a screw would make little if any difference in accuracy for smoothbore. The screw is just a keeper for the wad after all, slug and wad are lined up by other means.
In fact, if you use a tapered pin in your mould to provide a starter hole for the screw I have to think it would be so close to center that at shotgun rifling twist of 1:36" or so that there would be no worries. A 1:10" twist might be a different matter but you won't be worrying about such a fast twist in a shotgun bore.
A hot melt adhesive might do better with polypropylene than a two part adhesive or typical glue.... not that I have tried hot melt glue on polypropylene.
Could you re-engineer a bit and make the wads a snap fit onto slugs?
Just thinking out loud here.
Hmmm, if you consider the source, I haven't been very successful as of late. Oh, well.
Longbow
Perhaps an easier way of attaching the wads would be to use a thin base pin to cast a hole in the bottom of the slug, and then attach the wad with a pop-rivet.
On the matter of slugs with tails, this little chap is worth considering. He is a plug for catching predatory fish, and although he is exactly symmetrical in a left-right direction, that is the direction in which he will oscillate rapidly when drawn in. If the lip didn't give a downward force, it could be in all or every direction.
I believe the same is liable to happen when the drag-inducing body of a slug is extended too far behind the centre of mass, and certainly when it is shaped to reduce drag at the rear. That drag increases stability. "Rocket" slugs of marvelous beauty used to be illustrated in the Corbin swaging tools catalogue, and doubtless cost a fortune in tooling. But I doubt if their accuracy was that good.
A common dodge in nineteenth century France was to cast a nail-head into a round ball. It was said to give improved accuracy at long range, but not for sporting purposes. That would suggest that the nail oscillated and steered it in a spiral, making it quite useful for hitting an infantry battalion at more than usual musket range (although getting taken prisoner afterwards mightn't be much fun), but not for shooting game. I never heard of it reaching military service.
Attachment 140201
Last edited by Ballistics in Scotland; 05-24-2015 at 09:30 AM.
Things are coming together now.
Changed the design for the Brenneke wad to a more strong base and at the same time added a hole for a small self-drilling torx screw. Also modified the taper making it slightly larger - this removes any play between slug and wad and do away with the need for a assembly fixture. I use the mold for a slug-holding fixture while using a cordless drill with a torque clutch to fasten the wad. Fast and efficient - and I won't have to worry about the wad separating.
As you can see, this time my coworkers took pity on me and used a more manly color.
My supply of paper hulls are running low and I have trouble finding primers for them (Chevélot is the name over here, I believe you call them 57)
Therefor I'm looking into using ordinary plastic shells which you can have for the taking in unlimited numbers at the local range. A small problem - literally - is that all of them are truly low-base design leaving an awful lot of room for powder and slug. Loading the new "wad-less" slug in an ordinary 2-3/4 length shell it is impossible to get a decent roll-crimp. I started to trim the shells and ended up with a true two-inch case length before it looked alright. The Brenneke slug with 35 grains of BD under a 1/4" felt wad fits perfectly into a 2-1/4" shell.
So far I haven't done any serious testing. Mostly I have tried different powders for the sleeve-slug. The total weight of the slug is 460 grains (30 gram) while the Brenneke clone is 540 grains (35 gram) I was a bit worried about the short sleeve-slug and what it would do to the pressure. I tried Unique, but the loads seemed a bit erratic (didn't bring the crony along so can't tell fore sure) I then tried Vectan AS which is a fast burning shotgun powder. A load of 21 grains gave a very clean burn w/o any pressure signs. This will be the powder of choice for the sleeve-slug. All the shooting so far has been off-hand so no real indication of the precision potential (four shot in five inches at 35 yards), but the holes showed no sign of wobbling.
Next step will be a new roll crimper with more support for the shell wall. The original Brenneke has an extremely deep crimp and I would like to duplicate it. While the exposed nose looks kinda cool it could spell trouble in a tube magazine. Stay tuned for next chapter
Cute, aren't they...
Cap'n Morgan
I like 'em both! And yes much more manly.
Do you put a gas seal under or does the sleeve/attached wad have integral seal?
I will be looking forward to groups shot off the bench and which is more accurate... if there is a difference.
Longbow
This is looking extremely good. I would be very surprised if plenty of range testing doesn't reveal the groups to be markedly better than those four shots, and carried to longer range than most smoothbore groups. The full length wad in plastic should enable it to work better than most Brenneke style slugs to shotguns of different bore diameters.
One advantage of so much unused powder space is that it would enable you to use a thick wad rather than a thin one, between the powder and the plastic sleeve wad which is integral with the slug. That means you could include card discs solid enough not to be forced into those holes in the rear end.
The self-tapping screw should be fine for the loading enthusiast, but it might be a bit much for mass manufacture, and I believe if this works as well as it looks like doing, you should be looking for a manufacturer to adopt the design. In this situation an integral lead spigot should give enough of a hold, if it is peened over in a slight bell-mouth of the hole in the plastic.
BIS:
Great idea for assembly of Cap'n Morgan's slugs. That would keep bits to a minimum and allow rapid and easy assembly. I was thinking along the same lines for my cast on wads for the same reason ~ to eliminate screw installation. Simply cast a slug, peen over the end of the spigot then place in a form to cast on the wad. Even better for Cap'n Morgan as the spigot would be dead center and no chance for misalignment of the wad. A slight taper on the spigot and matching taper in the wad with a slight press fit would ensure location, then peen.
I am looking forward to these tests.
I can't decide which slug I like better but since I have had best results with slugs in wads, I think I would prefer the slug in sleeve unit by a little bit.
Both are excellent though and I hope both work well for you. Well done!
Longbow
The spigot idea is neat and certainly what I would look into if this was a commercial project - it would be easy to design a fully automatic assembly machine. Still, the screw method is pretty fast and the hole in the wad is a perfect fit with the point and the head of the screw, removing any chance of misalignment.
For the sleeve-slug a small rim at the top would make assembly a snap - so to speak - as it is now, a dab of glue will do.
,
Longbow.
The "sleeve-slug" was meant to be self-sealing, but I will try it with different plastic/felt wad as buffers. I dug out one of the slugs from the berm. The sleeve was nowhere to be found, but the (alloyed)slug had a clear imprint on the base from the support cross in the sleeve. Clearly there are great forces at work during launch - and that's at perhaps only 1200 to 1400 fps. I'm beginning to see what the high-speed cast boolit guys are up against.
Cap'n Morgan
For either the sleeve wad or the short one, the spigot could be cast with a slight lip to snap into place in a chamfered rear edge to the hold in the wad. The idea of a lip snapping into place in front of the slug would work if it could be done, but it would add to the problems of extracting the plastic wad from the mould. The chances are that the detached wad you describe occurred on hitting the target or berm. It is in flight for around fifty times as long as it is in the bore, and that gives a lot more time for frictional heat to penetrate and soften the plastic.
You are lucky to have the injection moulding facilities. But for other people, the internet is full of articles on how to make a pourable biodegradable plastic from starch.
One benefit of having a fairly thick wad behind the actual lead-and-plastic missile, would be that when all that escapes the muzzle and emits a momentary jet effect, it would be some way behind what is intended to move in a straight line. That might be less inclined to impose a wobble.
Last edited by Ballistics in Scotland; 06-14-2015 at 06:06 AM.
Cap'n Morgan:
Yes, HUGE forces are at work behind those slugs. I have recovered many slugs, both commercial/factory and home cast, that show significant distortion from the forces of firing. The base of the slug sees very large forces being generated by 10,000 PSI +/- for typical loads.
Pure lead runs about 2000 PSI tensile and 8% antimonial lead heat treated runs up to about 12,500 PSI tensile. So, anything less than high antimony heat treated slugs are very likely to yield in some way at firing. This is why I abandoned HB slugs. Everyone I recovered was distorted in some way at the skirt, even Gualandi DGS slugs. If obturation or distortion is the same every time it really shouldn't matter as long as it is concentric and consistent but then fits have to be perfect which for shotshells in long chambers with forcing cones is not necessarily an easy task.
Anyway, The slug needs to have lots of cross sectional area and good support under to avoid distortion at firing.
Have you tried heat treating any of your slugs for comparative testing with your regular slugs?
How do the ribs look on recovered full bore slugs?
I think you are getting very close with your designs. Keep up the good work.
Longbow
A momentary setback!
Today I tested a few of the sleeve-slugs for accuracy. At the third shot I caught glimpse of something bouncing off the ground in front of the target. I went looking and, sure enough, there was the sleeve wad without the slug, split halfway lengthwise and with the inner core crushed flat. After a short search I found another wad in an equally sorry state:
Well, that was a bit of a downer to put it mildly. I also brought along four rounds of the Brenneke clone and decided to try them without hoping for much, but lo and behold! A nice three inch group at exactly 45 yards. Clearly this wad was working as it was supposed to do and just as well as the various machined and cast wads I have tried so far.
On my way home I realized I had made a blunder when using Polypropylene (PP) instead of polyethylene (PE) for the wads. While PP has a higher tensile strength than PE, PE has much better impact properties and is also what is used in "normal" wads. I chose the PP for a more rigid wad with better stiffness, but this was obviously a mistake! No doubt the fact that the 'clones' was loaded with a slow powder (BD) compared to the fast Vectan in the sleeve-slugs could have had some influence as well.
So the sleeve-wad is temporary put on hold until I have some new wads - this time I'll ask the guys to use high-density polyethylene - that should do the trick. If not, I will modify the mold to increase the strength of the support column. Perhaps I will first try loading a few of the old batch with Blue Dot or Herco and see what happens.
Longbow, you mention fragile skirts in hollow base slugs, but the funny thing is I never had any problems with my Brenneke clones and skirt collapsing. In this pic you can see what's left of a polyester resin wad still glued to the slug. (it was a failed attempt to lighten the wad by drilling it full of holes) Also notice the ribs are still pretty much intact after hitting the berm. I have never used pure lead slugs, but only various tough alloys.
Cap'n Morgan
Yes, that slug looks really good. I have to think your wads are taking the brunt of the load and are not swelling so distorting the slug skirt.
I have some recovered Gualndi DGS slugs that show significant skirt swelling and virtually every HB slug I have recovered, except for heat treated alloys, have distorted skirts to some degree.
You obviously have size and fit good and your wad isn't acting like a fluid and applying hydraulic forces to the slug. That is the downside of my hot melt glue wads. If I cast them integral with HB slugs where glue fills the cavity then it does apply hydraulic forces swelling the skirt. I have had attached wad slugs in shotcups clip the petals with the bottom edge of the skirt when it is squeezed outwards, even with thick skirt slugs.
Anyway, it certainly looks like you are on the right track here.
Longbow
Did a little test today to see if a slower powder would be less destructive on the wads.
I loaded a few sleeve-slugs with a 5/16" felt wad on top of 36 grains of Blue Dot. The previous load which wrecked havoc on the wads had a 1/4" plastic seal over 20 grains Vectan AS - the combined weight of both payloads was 500 grains or 32 gram. The slugs were shot into a brink of fine sand to try to recover the remains (I used the horrible pink sleeve wads as I reckoned they would be as easy to spot as a tarantula on a wedding cake)
All four slugs were recovered and the result was quite uplifting (the one in front is a non-fired slug for comparison):
Only one of the four slugs had shed the wad and this had clearly taken place well after impact.
Of course, by changing two parameters in one test (seal wad AND powder) I have sinned against everything that is holy in science, but the end result remains; The sleeve-slug works as intended when you don't kick it too hard in the rear. There was quite a bit of residue left in the barrel between shots and the next test will include a chronograph to check the actually speed. I will also check a few of the 'fast powder' loads to get a better comparison.
Cap'n Morgan
Depends on the wedding cake decorations and icing a bit... but those pink sleeves should be easy to spot in sand. Not very manly but handy anyway.
Looking good!
Are you still going to change material for the sleeves? I have to think polyethylene would be a better choice.
Anyway, it looks like you've proved another point here. Felt or cork should provide a bit of a cushion from the kick in the butt that poor little slug gets.
Keep it up Cap'n Morgan and you'll beat this yet (I think you are about there).
Longbow
Would a good gas seal like the x12x over the powder, then the felt not work? Maybe not enough pressure under the felt alone to burn powder thoroughly? Those look like they would put Mr. Piggy out of action. Nice!
That seems like a problem neatly solved. I would be surprised if the pressure is very different from 36 grains of slow powder, as compared with 20gr. of fast, so I think it vindicates the use of the buffer wad.
If the plastic sleeve makes a good gas seal, in theory you don't need the felt doing so, and, it is only a buffer.
This could let you out of using a material which is quite expensive if it is of good quality. A number of discs of corrugated cardboard might be fine, with the corrugations laid in different directions. I have some 5/16in. reconstituted cork notice board sheet, and various authorities have dismissed cork as a sealing wad, because it compresses longitudinally without much swelling laterally. If you do use felt, though, you might as well roll the edges in melted lube and use card discs before and after, which prevents leakage round and through respectively.
There is a lot less of a tunnel between you and the light now.
Last edited by Ballistics in Scotland; 06-17-2015 at 09:36 AM.
Total noob here when it comes to casting for shotguns, but I'm not sure this is 100% correct. I'm in the happy position of being able to both administer shotgun training for my department, and pick up the (low-recoil loaded) hollow-base slugs off the hillside after everyone else goes home. These slugs are a very soft 40-1 mix and since we have an impact area that's up a 300 yard slope, I find them in states ranging from nearly pristine with the rare cardboard wad still attached to "plane crash victim". The impression I get is that the base collapse is mostly from impact - the more solid nose starts decelerating, and the less-sturdy, unsupported base keeps moving forward. Fosters thus seem to expand in the opposite direction as hollow-points via this weird trick of momentum - from back to front rather than front to back.Originally Posted by longbow
At any rate, my reason for straying onto the shotgun page is to seek answers to the problem of bore leading with slugs. A stiff brush on a drill-chucked rod has been my answer, but would like to seek solutions that I might suggest to our ammo manufacturers that would mitigate the problem. Cap'n, it looks like you're doing well in the accuracy department, but how are your two wad systems working for cleanliness? And. . .while we're on the topic, has anyone thought to powder coat 12 gauge slugs?
WWJMBD?
In the Land of Oz, we cast with wheel weight and 2% Tin, Man.
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