Finned Slugs

[Tokarev]

They may stabilize if you add a disk behind the fins. Might be a headache to cast though!

[longbow]

I thought about that but if I have to add anything after casting I might as well make an AQ or Brenneke clone. I gave up on that for two reasons: it is time consuming and it is difficult to maintain precise consistency with added on bits.

I have had some pretty good results with AQ clones but they are a pain to make and I still get occasional fliers.

I mentioned in this thread or another that I got very good results (2" groups at 50 yards) with the Rapine 730550 (or is it 730560?). Anyway, it is a full bore hollow base that seems to shoot pretty well. I have been trying to equal that accuracy but with a slug that has a more solid construction.

I may just buy a Rapine mould and make a new hollow base plug for it if I am unsuccessful with my home made moulds. I am having fun though and that is what this is about.

Longbow

[Tokarev]

You may want to make a slightly different mold for the finned design and try it again. Should not be too difficult: instead of a tapered rear, use cylindrical body. That may actually stabilize.

I think I understand your mold design. The fins are made by the bottom punch. If you will turn your design upside down and leave space for a disk at the back of the slug, that may become more stable. But then, alas, we are back to Brenneke design!

[missionary5155]

Greetings This may be why all the AT rockets have fins that are either spring loaded to get out into "Clean Air" or are set waaaaayyy back from the nose.
I sure have no words of wisdom. It is a GREAT looking Idea !
MIke in Peru

[longbow]

Before I give up, I will try one more thing.

I noticed that there were some "foreign" bits in the "wound channels" in the wood but didn't think too much of it. Further examination of the slugs shows a dark blob on a fin. Again, I didn't think too much of it at first but... if these bits are chunks of nitro card wad (which they kind of look like) then it is possible that the 1/8" nitro card wad under the slugs was cut under the force of accelereation and hung onto the slugs causing uneven drag.

I would not have thought this would happen as the wad column is all hard card but maybe.

Next test, I will punch some poly discs to put directly under the slug so there is no doubt. If accuracy improves then there was likely passenger bits of card wad during this last test. If not, I am back to the drawing board.

Like I said, the balance point is just behind the start of the fins and about matches several Foster styles I have that fly reasonably well.

I will keep you posted.

If anyone is interested I can post photos of the mould. It is really quite simple. Obviously more interesting if it works!

Longbow

PS: The slugs shot into the wood went straight in and traveled straight ~ no tumbling.

[Blammer]

hey! the nitro card cutting may be the issue!

Stack a few of them poly cards, make sure they are not cut.

[Tokarev]

Wad following is a kiss of death. That's why the container wads became so popular IMO. Correct me if I am wrong.

[longbow]

Well, I haven't gotten out to do another test but I did do some more "analysis" of the recovered finned slugs and others.

After taking a good hard look at the remains of the recovered finned slugs, it was pretty obvious that the fins were compressed at the base. Most were shorter and fatter at the bottom.

As cast = 0.130" thick
recovered slugs = from 0.135" thick to 0.196" thick with most around 0.150" thick

Length of fins as cast = 0.650"
recovered slugs = 0.535" to 0.634" long

The finned slugs were loaded over a hard card wad column.

I also recovered some slugs shot into snow some time ago this weekend. These were Rapine 660500 and a home made wadcutter.

These were loaded into shotcups with cushion legs.

The Rapine slug has a fairly thin skirt so I expected some shortening but not this!

As cast length = 0.935"
Recovered = one at 0.755" and one at 0.785"

As cast Diameter = 0.665"
recovered = one at 0.704" and one at 0.693"

The wadcutter had a 0.100" skirt so fairly thick.

length as cast = 0.810"
recovered = 0.793"

diameter as cast = 0.651"
recovered flaired skirt = 0.701"

These were all ACWW over moderate loads of Blue Dot and the hollow base slugs were sitting in cushion wads with a hard card under them yet the skirts still distorted badly.

I have shot thin skirted hollow base slugs filled with hot melt glue and they seemed to hold up well without significant distortion.

I wasn't surprised that the thin skirt collapsed but I was somewhat surprised that the thick skirt distorted so much and also that the finned slug which has even more cross sectional area to support it showed so much distortion.

Lesson learned. Next time I will oven heat treat the finned slugs and possibly set them into a filler to help support them against acceleration forces. I will also heat treat and fill bases of the hollow base slugs to see if there is improvement.

More to come!

Longbow

[longbow]

Well, I got out to do some more slug shooting today.

This was to test the finned slugs again. This time:

- they were oven heat treated
- had 3 hard polyethylene disks under them
- 3 nitro card wads under those
- a cushion leg from a shotcup under that and 30 grs. of Blue Dot so lighter load

The gun is smooth cylinder bore.

I had high hopes for this test but alas, I have been defeated.

One shot hit a 24" x 36" piece of paper at 50 yards.

I managed to recover 2 slugs from almost 300 yards and they are virtually undamaged. No fin distortion at all. So the heat treating, cushioning and lighter powder charge worked to avoid distortion of the fins. In that sense this was a success. However, it still didn't result in accuracy.

I also recovered several slugs from previous experiments. In the attached photo:

- far left is a Rapine 660500 unfired
- 2nd from left is a Rapine 660500 recovered from deep snow (obviously needs a filler to support the skirt)
- 3rd from left is a thick skirt wadcutter hollow base that was loaded into a shotcup and recovered from deep snow (thick skirt has collapsed a bit and belled unevenly)
- 4th from left is a TC thick skirt hollow base that was loaded into a shotcup (thick skirt has collapsed a bit and belled unevenly)
- 5th and 6th from the left are recovered finned slugs that hit soft sand at around 75 yards then bounced to almost 300 yards. Virtually undamaged but no accuracy to speak of.
- 7th & 8th from left are the two finned slugs recovered from wood during the last test. These were ACWW and the fins did distort and swell at the base due to firing.
- 9th from left is a homemade AQ clone. Some of these have shot very well but I still get wild flyers.
- right side is a 0.735" round ball. I recovered several of these also shot into deep snow and was surprised to see an uneven flat around the equator. This one was the worst example but several showed a noticibly uneven flat. This was loaded over hard card wads.

All of these were loaded over Blue Dot and charges ranged from 33 grs. to 38 grs. depending on slug and weight.

Of all the homemade slugs I have shot, so far the most consistent groups have come from the wadcutter, the TC and round balls (tight fit in shotcup or bore size). These groups were not spectacular and ranged from 4" to 8" at 50 yards but they were consistent.

I am sure better accuracy can be had than I am getting but the lessons learned here are:

- that the slug has to be well supported and guided into the barrel
- even thick skirted ACWW hollow base slugs belled at the base so thicker skirts, heat treat or fill to preven distortion (or maybe all of the above)
- for moderate ranges to 50 yards the good 'ol round ball does pretty well and is easy to load
- extreme consistency is required when attaching wads or skirts Brenneke/AQ style (I am sure the flyers are due to slightly uneven skirts)
- cool looking finned slugs don't seem to work!

So, onward and upward! Since the finned slug is a no go I will rework the mould to make a ribbed hollow base. Test results to follow.

Longbow

[longbow]

Well, I got some slugs loaded and ready to shoot. Drove all the way to the range to find that there was a cowboy action shoot in progress! I don't think they would have liked me shooting 12 ga. slugs during their shoot.

Fortunately I had also taken the bows so my wife and I did two rounds at the archery range.

The slugs will have to wait a little longer.

This time I have loaded:

- 5 Rocket Slugs diehard sent me
- 5 of my finned slugs machined down to fit into shotcups like the Rocket Slugs
- 5 full bore finned slugs but this time loaded over a cushion leg
- 5 TC slugs form a home made mould loaded into shotcups
- 5 full wad cutter slugs from a home made mould loaded into shotcups
- 5 0.662" round balls drilled with a sheet metal screw inserted then set over a 5/8" long piece of 1/2" copper pipe filled with hot melt glue ~ these are kind of Brenneke like and weigh 570 grs. then loaded into shotcups

All the above are loaded in Fiocchi hulls over 34 grs. of Blue Dot.

Diehard said the Rocket Slugs did fairly well so I am hoping. I am also hoping that the shotcup and/or cushion leg help my finned slugs.

I had given up on the finned slugs until diehard got good results with the Rocket Slugs. I like the design so am hoping I can get them to work. I also took lots of photos of the Rocket Slugs and got all the dimensions I could get so I can reproduce them if they work.

Hopefully next post I will have some range results to share!

Longbow