12 gauge Lee slug Improved

[yondering]

Thanks to some inspiration from bearmn56’s lee slug modifications, and a donor mold from sargenv, I’ve been experimenting with some modifications to the Lee 1 oz 12 gauge slug mold, and here’s what I’ve come up with.

My goal was to increase the weight and improve the nose shape of this slug, while hopefully improving accuracy as well. Since this slug is intended for rifled barrels, the hollow base foster design (intended for smoothbores) seemed out of place. I started by grinding down the mold’s center pin, the “key drive” section, to make a mostly solid slug with ~ 1/8” of the key drive portion remaining. I fired a few, and found the wad wasn’t pressing up against the solid inner base of the slug, so there was still empty wasted space inside. I then ground the key drive section down to .070”. I have not fired these yet, but my intent is for the wad to form into the key drive shape, completely and evenly filling the empty cavities at the base of the slug with no wasted volume that could be filled with lead.

I’m not a big fan of the round nose design of this slug, so I wanted to give it a larger flat nose. Because it’s a nose pour design, and the center pin is a smaller diameter than the slug OD, I couldn’t grind a full diameter reamer to change the nose shape. I thought about grinding a D-reamer that would fit through the center pin hole, but started looking around for other tools on hand that would do the job.

To run a reamer in through the center pin hole in the mold, though, the mold would need some alignment pins. The ridge on the key drive center pin aligns the mold halves vertically, so without it in place, the 2 halves will be out of alignment. I solved this by installing a couple alignment pins like most traditional mold halves use. I used the shaft from a worn out dremel bit for the pin material. 2 holes were drilled through the mold blocks (while assembled), then the pins were pressed into the holes in one block. After enlarging the holes in the other block and using a countersink, it was ready for nose profile modifications.

First I tried a ½” diameter countersink. This worked fine, and gave the slug a .40” meplat diameter, although it was hard to keep the countersink perfectly centered in the mold. This meplat was still smaller than I wanted though.

Looking around some more, I spotted my LE Wilson case deburring tool. Aha! The diameter of the deburring tool body is ~ .015” smaller than the center pin hole in the mold. Perfect! I chucked the tool up in my cordless drill and spun it slowly in the mold. This gave the slug a nice truncated cone shape, with a .450” meplat diameter. Final weight is right about 515gr, although this particular mold casts slugs a little shorter than others, so most molds with these same modifications would probably run 520-525 gr.

I’m hoping to try these this weekend or next, I’ll post a range report at some point.

Here are some pictures. Keep in mind this is a resurrection of a damaged mold, with lots of dings in the cavity edges and a detached key drive section, so it's not as clean as a new mold would be.

Center pin, key drive section ground to .070”. The key drive section and the lip around the base have been cleaned up a little on the belt grinder, so the key drive is smaller diameter than original.
http://i24.photobucket.com/albums/c26/zthang43/molds/IMG_2956.jpg

Staking center pin back on bracket
http://i24.photobucket.com/albums/c26/zthang43/molds/IMG_2961.jpg

L.E. Wilson deburring tool in cordless drill
http://i24.photobucket.com/albums/c26/zthang43/molds/IMG_2946.jpg

Reaming the nose
http://i24.photobucket.com/albums/c26/zthang43/molds/IMG_2951.jpg

Nose modifications complete. Notice alignment pins.
http://i24.photobucket.com/albums/c26/zthang43/molds/IMG_2954.jpg

Re-assembled mold, ready to cast
http://i24.photobucket.com/albums/c26/zthang43/molds/IMG_2932.jpg

Original Lee slug and “Improved” slug bases
http://i24.photobucket.com/albums/c26/zthang43/molds/IMG_2974.jpg

Left to right: Lee original, ½” countersink nose, deburring tool nose, Lyman 525gr slug
http://i24.photobucket.com/albums/c26/zthang43/molds/IMG_2964.jpg

Meplat diameters: .310” original, .400” countersink, .450” deburring tool, .550” Lyman
http://i24.photobucket.com/albums/c26/zthang43/molds/IMG_2981.jpg

[tommygirlMT]

I am eagerly awaiting range reports. The resulting slug looks very clean aerodynamically. I'm thinking it will probably have a better BC then the Lyman.

The Lee slug does work in either a smooth bore or rifled bore and was designed as such --- to work in both. That is why the original has such a deep HB and is built like a foster slug. Your version is probably going to be superior for rifled barrels and doing what bearmn56 did namely making a thicker skirt by turning down the diameter of the HB pin and making a thicker nose by reducing the HB pin length would be the method of choice for someone who is shooting and loading for a smooth bore gun since it would still have a HB and would probably still work out of a smooth bore gun. I really like your method of using the case deburring tool to re-cut the nose. I think that should be done whether one intends to use the slug for a smooth bore or a rifled slug bore. I don't like the round nose profile either. A Postal or Creedmore nose shape makes sense for a very heavy (800+ grain) full bore 12ga. solid slug intended to be shot like a BPCR at extended range like artillary but any kind of rounded tip nose makes absolutely no sense within normal slug shooting distances of 150 yards or less for a rifled bore slug gun or 100 yards or less with a smooth bore gun and more like half those distances being the norm.

Also, excellent how the weight turned out. Now you can load them using the Lyman slug data as a starting point and just use a wad with a longer crush section and shallower shot cup substituted. Such as substituting a Fed 12S0 for a Fed 12S3

[eye shot]

The Lyman still has one big advantage over the Lee, it's longer.

[yondering]

doing what bearmn56 did namely making a thicker skirt by turning down the diameter of the HB pin and making a thicker nose by reducing the HB pin length would be the method of choice for someone who is shooting and loading for a smooth bore gun since it would still have a HB and would probably still work out of a smooth bore gun. I really like your method of using the case deburring tool to re-cut the nose. I think that should be done whether one intends to use the slug for a smooth bore or a rifled slug bore.

Yes, I agree. A modified nose with the original hollow base would help keep more weight forward as well, and might even shoot better than the original. Since I'm intending my slug for rifled bore use, I didn't think to try modifying just the nose first for smoothbore use. I've had such good results from the Lyman slug and roundballs from a smoothbore that I didn't bother with the Lee.



Also, excellent how the weight turned out. Now you can load them using the Lyman slug data as a starting point and just use a wad with a longer crush section and shallower shot cup substituted. Such as substituting a Fed 12S0 for a Fed 12S3

My thoughts exactly. Not to mention, I've run into a few loads where the Lyman is just a little too long to get a good crimp on the hull; the Lee would work fine in those.

eye shot, the length of the Lyman slug can be an advantage or a disadvantage, see the paragraph above. When they are fired, esp. with heavy loads, they tend to get real short unless cast very hard, so the shape "as cast" is not necessarily what they look like in flight.

I really don't know if this modified Lee slug will shoot as well as the Lyman, or worse, or better. It was mostly an excercise in "what if", with nothing to lose, as the mold wasn't functional when I got it.

[sargenv]

People say that the Lyman slug compresses under load so that in reality it is shorter when fired. Has anyone done any research in some kind of Sabot support to keep it from compressing like it does? I'm not sure what we would use though.. And any kind of filler that doesn't disperse may cause it to fly funny..

[eye shot]

I read that a slug length should be at least twice it's dia. for accuratcy. If you can't get a good fold crimp on a Lyman a roll crimp will give you more room, and if that isn't enough can always go to a 3" hull. I use hard cast 525's and the ones I dig up at the backstop are very close to length before fired. Yondering great thread!

[yondering]

I read that a slug length should be at least twice it's dia. for accuratcy.

I don't think that's true. The lyman slug length/width is only 1.13:1, definitely not 2:1! And for rifled use, it all depends on twist rate. Most of the rifled barrels available are too fast twist for any of the slugs we're discussing here.

[turbo1889]

I read that a slug length should be at least twice it's dia. for accuratcy. If you can't get a good fold crimp on a Lyman a roll crimp will give you more room, and if that isn't enough can always go to a 3" hull. I use hard cast 525's and the ones I dig up at the backstop are very close to length before fired. Yondering great thread!

For a smooth bore foster type slug that statement is absolutely false in every sense. An excellent example of this is the Lyman 350gr. 20ga. wad-slug which is longer then 12ga. version and smaller diameter. It is NOT stable in flight from a smooth bore and will key-hole badly.

For proper stability for foster type smooth bore slugs a length to diameter ratio between 1-1/4 to 1 and 1 to 1 is normally considered best.

Now if you start talking about attached base wad slugs such as Brenneke type slugs where you are using a much lighter weight material for the tail section then this ratio does indeed change and your 2:1 estimate is very good - but for foster type slugs where you must use the same density material for the tail as for the head ratios that high don't work.

Believe me I know - In the course of my ongoing extra heavy weight 410-slug research and development project which has been going on now for well over four years I have literally test fired hundreds of potential drag stabilized smooth bore projectile types of all different configurations and length to diameter ratios.

HB Foster Slugs, Sweet spot:
------------ Length to Diameter Ratio = Between 1-1/4 to 1 and 1 to 1
------------ HB Depth = 2/3 to 1/2 Slug Length
------------ HB Diameter = 60 to 70 % of slug diameter
------------ Optimal Bearing Length = 65 to 85 % Slug Length
------------ Optimal Super-Sonic Nose Shape = 40 to 60 degree angle TC or SWC
------------ Optimal Sub-Sonic Nose Shape = Round Nose Flat Tip

Still working on defining the sweet spot for Brenneke type slugs - here is what I've got so far:
------------ Length to Diameter Rate = Between 2-1/2 to 1 and 1-1/2 to 1
------------ Tail Length = Minimum 1/3 of total Slug Length
------------ Optimal Nose Shapes Same as HB Foster Slugs

[Harmon_Greer]

what kind of accuracy are you getting?
i modified my lee 1 oz mould yesterday with my deburring tool.

it now has a larger meplat and weighs about 500 grains.

i loaded some in win aa hulls, fed primers, waa12r claybuster knock offs with 28 grains of unique.

they shot into one ragged hole at 45 yards. this is better than previously as the unmodified slugs would not shoot two rounds touching at that range.

i plan to modify the base pin next...to add more weight.

[inuhbad]

EXCELLENT posting!

I'm eagerly awaiting some range test results and more pics! :drinks:

I'm just getting started loading Lee 7/8oz slugs, and this might be a good mod to get the weights up a little better...

[yondering]

I was able to shoot a few of these this weekend, but can't really comment on accuracy of this particular slug. I got poor accuracy with all the slugs I fired, including the Lyman. I think my problem is the porting in my barrel; it's tearing the wad petals off, and I can feel some slight burrs inside. This slug project will have to be on the back burner until I get the porting smoothed out.

If it was a smoothbore I could hone out the ported area, but this is a rifled bore, so I'll have to figure out something creative. I might just cut the barrel back to get rid of the ports; I didn't want a ported barrel for this reason, but a decent trade was offered so I took it.

[Doc Holliday13]

btt

Did you try these in a different barrel yet?

[JIMinPHX]

That's an interesting way to beef up a Lee slug.

The new slug is obviously going to weigh more. What do you do for loading data?

[yondering]

Haven't tried these in another barrel yet, sorry. I've been away from this forum for a while, and spending all my time on my dual sport bike.


That's an interesting way to beef up a Lee slug.

The new slug is obviously going to weigh more. What do you do for loading data?

Well, for loading data, I proceeded very carefully. :p
Actually, since it's very similar in weight to the Lyman slug I have, I used the same starting loads. Obviously the shorter Lee slug left more room in the case, so I used cork wads on top of the slug.

I haven't taken the time this one needs to develop some accurate loads yet.