New Slug Family

[longbow]

After recent discussions with some folks on shotgun slugs and also after reading Cap'n Morgan's post on his Brenneke I decided to revisit a slug design I tried a while ago but with some modification.

Back in 2009 I tried 0.662" round balls drilled for a screw then set them screw up and put a piece of copper tube on top then pumped full of hot melt glue. The came out pretty well and while the wads look bad, the slugs shot pretty well.

The first three photos were posted after shooting in 2009. the next two are the punch/die set and finished bore size slugs.



My reason for trying this was to get nice consistent edges and surfaces which I was not able to get with other forms of Brenneke style slugs. These 0.662" balls and copper tube are a little undersize for standard shotcups so had to be "patched" up to snug slide fit in the barrel.

I tried flaring to bore size using a tube flaring tool but as you might guess, it didn't go too well and I got uneven flares.

In any case, after recent discussions, reading posts and thinking some (always dangerous!) I decided to try making a bore size version again so made up a set of punches to flare and used a short piece of 12 ga. barrel as a female die to limit the flare.

I cut 3/4" lengths of 1/2" copper tube, set onto the short lower punch, slide the barrel section over top, then drop the top punch in and whack a few times with a small sledge. They come out very nicely, quite quickly and they all look the same. They have a nice slide fit to the barrel too.

Then I drilled 0.678" round balls and put short screws in them, set them onto cupped holders with screws up, set a copper skirt on and pump full of hot melt glue.

The resulting assembly weighs 610 grs +/- a bit which is heavier than I would like but a smaller ball would fix that or I can modify a mould I have to make a short Hammerhead like slug that fits into the tube a ways.

The balance point is just ahead of the front copper tube flare so not far behind the center of the ball.

The ball weighs 460 grs. and the tube & glue weigh about 150 grs.

These are intended for smoothbore and I really like the Brenneke and AQ style factory slugs but have been unable to get consistent base wads so far. I have tried jigs and a variety of materials but so far the best for me has been hot melt glue poured into a form set onto the slug. The copper tubing should make for a consistent skirt... I hope anyway!

Another problem I ran into with ribbed Brenneke style slugs was that the ribs collapsed allowing the slugs to tip in the barrel. I tried wider ribs but with limited success. The copper tubing should solve that.

These really aren't a lot of work to make using the punches. It goes pretty quick.

Let's hope they shoot well!

I will post range results when I have them.

Longbow

[Cap'n Morgan]

The copper tube wads looks interesting, they should certainly prove sturdy enough. If you could find some aluminum tubing in the right size it would reduce the weight considerably. I've been contemplating using hard-pressed paper mache, mixed with some sort of glue to increase the strength - molded/pressed into a fixture and with a self tapping screw to hold it securely in place, but I'm not sure it will seal well enough.

You're probably right about the wad being the secret to success. Getting the slug/wad aligned with the bore is not easy when the difference between bore and chamber is 0.08 or even larger, and the thickness of a modern plastic shell is only 0.024. Perhaps a good old-fashioned paper hull would be better suited for slugs?

[longbow]

Cap'n Morgan:

The original Brenneke used a hard felt wad between two washers of what looked to me to be a hard cardboard. Whatever the assembly was, it retained its shape after firing. What I have found in the testing I have done is that even nitro card wads delaminate and distort under the stress of firing.

I've tried cushion legs drilled and screwed to slugs but those distort really badly and leaked gas in a big way ~ in my testing anyway so I gave up on that.

I tried nitro card wads which delaminated/distorted.

So far the best I have found is hot melt glue poured into a form over the slug and that works pretty well but... you need a good release agent on the form and you can't use it for full bore slugs without a paper tube or something to keep the glue off the bore.

I started out wanting full bore slugs but in the majority of my tests, wad slugs gave better accuracy and were easier to make/load.

My ribbed Brenneke style tended to crush the ribs and I really don't know why. There was a long bearing surface and there should not have been any tipping force from wads but tip they did! The tipping caused crushed ribs and poor accuracy. Taking the same slug and turning it down in my lathe to fit into a shotcup worked better with better accuracy.

I originally tried the copper tube as an attempt to get good clean edges and no distortion at firing. That part worked but making them then patching up to fit into shotcups was a bit tedious and they didn't seem to work any better than round balls to 50 yards anyway, so I didn't pursue it.

Recently I have gotten interested again and had some information exchanges with a few people and decided that the hard copper as a bearing material might prevent tipping/crushing and provide better bore alignment than something with a relatively soft skirt.

The punch set while crude works and made skirt production pretty easy.

If this shows promise, I will scale it down to fit into a shotcup as well since I have generally has best results using shotcups.

Lighter tubing would be better for sure. Aluminum should work if I can find the right diameter. Plastic tubing would probably work too but it would have to be filled with hot melt glue for sure and it could not be brittle. It would have to be fairly flexible but tough like Nylon or Delrin.

I have thought about using Nylon or Delrin rod turned to size and screwed onto a slug but it is just too much work to make and shoot many. I am lazy so want something that doesn't take more time than I am willing to put into it.

Copper tube is readily available, easy to work with and relatively inexpensive.

You mention sealing and coincidentally I just ran a series of tests where sealing (or lack of) was a big issue. I had a bunch of shotcups left over after I cut the gas seals off for use under full bore slugs so I decided I wanted to test another idea ~ I got it in my head that cushion legs might be causing tipping of the slugs at the muzzle because the cushion legs aren't really forced to stay flat, they just crush up against the bottom of the shotcup. Anyway, I decided I would use a hard card wad column to ensure no tipping and put slugs into the shotcups with no cushion leg or gas seal.

Well, that didn't go so well! The gas leakage past nitro card wads and hard card wads was impressive! Recovered shotcups have gas cutting streaks and tears and some petals burned right off! I would not have thought that much gas would get by nitro card over powder wad then a 1/2" hard card but it did.

Another lesson learned ~ use plastic gas seals! They work and work well... way better than card wads.

So, I am back to full bore slugs with copper tube skirts for now (along with plastic gas seals under!) and I will see how this works out.

I will certainly be interested in seeing your slug assemblies and shooting results as well. I like your mould and I really like the traditional Brenneke style slugs. Good luck with that!

Longbow

[hubel458]

We can get cards and wads of about any size.Could use right size ones
inside the copper tube, with strong plastic powder seal, with a screw though the
whole works into the lead ball,....Find a seal that tubing would set into a
step or shoulder on. All parts could be put in die. in a drill press, hole drilled
in one pass, and screw put in, and done. Ed

[longbow]

Ed:

That might work too but in all honesty, these are pretty easy to make. The biggest problem is drilling the hole in the ball ~ I use my lathe. My TC slug mould has a base pin that leaves a screw hole in the slug at casting but it was the wrong diameter slug for this tubing. If these do work out then I would look at either a "hollow point" pin in a round ball mould or using a Hammerhead like slug that has full bore nose on it and a short mushroom stem to line up inside the tubing and cast with a screw hole in it. Now if that slug was a press fit into the tube and nitro card wads pushed into fill up the empty space there would be no screws. That might be something to work on!

Where I have run into issues with a screwed on gas seal is leakage past the screw. With sealed tube that might not be an issue.

So far I just run a screw into the ball, set the tube on top with screw sticking up and pump full of hot melt glue. They come out pretty good.

But you are right too in that with card wads inside the tube they are protected and not exposed to drag causing flight deviations if they distort.

I think however it is done all that is really important is consistency and nice clean edges and surfaces. That has been my challenge.

Compared to your work Ed, I am an amateur. I really like some of your attached wad slugs, those are great! I am still playing around with my old smoothbores just trying to stretch accuracy out some with home made stuff.

Longbow

[hubel458]

Maybe to stop leakage around screw we compress the fiber wads a little,
which would also expand them and hold tighter against inside of copper
tube making the whole works stronger.And use slower powders
like our loads which are much easier on seals, etc,
I checked a short piece of tubing here and it fit the outside step on
top of BPGS powder wad perfect. Got to find ball and
make up one. We got all sizes of wads to use in boxes
that I traded for years ago.Bushels of them.. Ed

[longbow]

Ed:

That's a good idea!

I know you have commented on the fact that your loads are low pressure due to the slow powders you use so that would certainly be easier on wads, seals and shoulders for that matter!

Do you have pressure tested loads available? I would certainly buy the hubel458 slug loading manual if it was available!

Thanks,
Longbow

[hubel458]

The ones we lab pressure tested is 600 gr and 720gr fullbore slugs in 3" case,
both at 14,700 psi, same as 3.5" magnum specs for modern
alloy steel guns and barrels. Roll crimped using 4759 powder.
600gr with 95gr over 1900, 720 with 90gr over 1800.

Our loads are low pressure in the sense of the peak pressure
in relation to the overall taller than regular shotgun loads, average pressure
curve. Which the plastic cases can stand, and the overall bigger average
of the curve gives the load big power and the cases still working safely.
Those 14,700 psi loads are max working pressure for plastic
depending on the brand of the case, with the
plastic still being easily resizable for reloading.Ed

[longbow]

600 grain slug is about as heavy as I would want to go I think. I guess if the acceleration is slower with the slow powder then recoil probably isn't as brutal as one might think from the velocity achieved though.

I have not used 4759. Are there any ignition issues with lighter loads... or is there a recommended minimum starting load?

Thanks,
Longbow

[longbow]

Well, another range day failure!

I had high hopes for these slugs but ran into an unforeseen problem (unforeseen by me anyway).

The leading edge of the slugs cut the hulls!

I had thought that the leading edge flare might catch the crimp and tear it which wouldn't be good. However, I did not think that the edge would dig into the side of the hull and cut a big chunk out but so it did!

The first one was fine though recoil was "brisk"! The second one seemed to shoot okay then the third but as I removed the third hull I noticed the big chunk of hull missing. Yikes! I checked the first one which was fine and the second which also had a large piece missing. Yikes again!

I decided I would not shoot the rest.

I think the slugs themselves are fine and should shoot okay but that narrow driving band is too sharp so back to the drawing board!.

I may try to swage them with a straight cylindrical driving band which if I can do it easily should solve this problem and not affect the slug. Or I will revert back to shotcup size and simply flare the trailing edge of the skirt to snug fit in shotcup. Then the ball is the front driving band.

Even at bore size they drop into the hulls loosely so I guess there is enough clearance to tip at firing and grab a bit of hull with that flare. OOPS!

So, once again, no good groups to post! I will work to remedy that!

Longbow

Hmmmm, had a thought while walking the dog. It may also be possible that the copper tubing flared even more under acceleration with the ball pushing on it maybe making it dig into the hull.

[hubel458]

You want to use no less than 75gr 4759 in 12ga,
Maybe wads compressed inside copper should helpalong with using slow powder.
Also maybe make them up smaller to ride in wadcup.Ed

[longbow]

Ed:

Yeah, I didn't mention the load:

- Fiocchi 2 3/4" hull
- 32 grs. IMR4756
- plastic gas seal
- nitro card wad
- small scoop of COW to make sure the glue doesn't stick to the shotcup
- 610 gr. copper skirted slug
- fold crimp

The slugs are a loose slide fit in the bore but no rattle. They will almost fall through under their own weight.

If ball set back causing the flare to expand is an issue then a slower powder would probably be better. I have not tried your loads yet.

I just finished modifying my punch set so that I get about 0.100" bearing surface at each end now but as I suspected, the extra working of the copper results in slightly uneven swaging... not much and it may not make a difference but there is a slight wobble when I chucked them in my lathe to check. It may not hurt and I will try a half dozen or so to test

The copper tubing is slightly small in diameter for direct fit into a shotcup without either flaring or patching. In my first post there is a photo of two recovered slugs dug out of the 100 yard berm. While the wads look pretty bad accuracy was not too bad at all. These were patched to take up the clearance and give snug fit in the bore.

Generally, I have had better smoothbore success using slugs in shotcups. I think the shotcup helps steer the slug through the forcing cone and probably cushions some too. In any case, it has worked pretty well for me so far. So, I may also try making a smaller die to produce a 0.675" flared copper skirt for use in a shotcup. Of course the skirt has to be a bit shorter but it should still be okay. 3" hulls and heavy payload shotcups would allow a longer skirt.

Experimentation is not over yet!

Longbow