3d Printed Shotgun Wads

[mikehill85]

I have been casting and reloading the Lyman 525 slugs for a bit over a year now. To save money I have basically just been using Walmart Field and Target multi-purpose loads, pouring out the lead, casting the lead into the 525 slugs and re-crimping them (fold crimp). I am currently getting ~4" groups at 50 yards.

I think some of the major accuracy problems with this slug and using a shotcup as a sabot are 1. Shredded wad petals and 2. The diameter of the driving bands on the slug. I am an Engineer and have a 3d printer. I was considering increasing the diameter of the front portion of the Lyman 525 slug by 3d printing a cap for the front portion of the slug, out of nylon, which would bring the front driving band up to 0.72 inches (a bit less than bore diameter for safety), a rear truncated cone to fill the cavity with a ball on the end similar to the Truball slug and printing my own wad with a recess for the ball similar to the Truball slug. I would actually just copy the Truball slug wad in a program like Fusion360.

Any thoughts on whether this is a terrible idea or not? Is 0.72 inches too big or too small for the front driving band?

[gpidaho]

Mike: The printed cap to bring the Lyman sabot slug up to a bore sized slug sounds interesting. I shoot cylinder bore or rifled slug barrels so .720 sounds small to me. In my smooth bore cylinder barrels I shoot up to .737 round ball. The Lyman doesn't have a very large drive band so my thought is that the cap should bring the size up in the .730 range. Take all this knowing that I'm no expert at all this, just sharing my thoughts. Gp

[mikehill85]

Thanks for the input. The choke tube with the least constriction I have is improved cylinder bore so I thought it might be best to make it 0.72” because that’s the diameter of the choke tube but in reality I’m sure 0.73 is fine too, especially if I put “rifling” in cap the design to give it some wiggle room like in “rifled” slugs.

[littlejack]

Mike:
So, you are saying you are going to do away with the shot cup altogether,
then you are going to enlarge the front driving band diameter of the projectile via a cup over the front end, Yes? Then, you're going to make a cavity filler piece with a oversized base wad attached, right? So, the base of the original slug would still be undersize (as cast) but your 3d wad would be bore size, except for the cavity filler in front, right? Mike, that is a real mindbender. I understand the concept, but that sounds like a lot of work.
Now, back to the basics. Before you insert the substituted slug for the shot, have you removed the wad from the shell, and made sure the wad petals are the correct thickness for the slug. The Lyman slug, has two (2) diameters. The front driving band is approximatey .010 larger than the skirt diameter. Therefore, the cup petals need to be two different thicknesses, to accommodate the two diameters of the slug. This may be why you are getting shredded petals on the wad cups.
Anyway, "Necessity is the mother of invention". You are trying something completely different. Not a darn thing wrong with that. I'm posting another procedure I'm going to try with the Lyman slugs. You may be Interested.
Let me know if I understood your procedure correctly.
All the best in your endever sir.

[mikehill85]

Yes, I think you've understood me right. I would take out the old wad with shotcup and put in a new one which is basically a copy of the federal tru ball slug wad. I would have a cavity filler like the ball in the truball slugs and I would have a cap that brings the front of the slug up to bore diameter. The slug should be centered at the front by the cap and at the back by the wad. The ball should ensure separation from the wad.

It might not even be necessary to have a custom wad, it is possible I could just cut the petals off a wad with shotcup, fill in the cavity to make sure that wad doesn't get stuck in the back of the slug (creating flyers), extend this down a bit and around the rear of the Lyman slug bringing the back driving band up to bore diameter as well. I may try this first as a test as it is much simpler.

Ideally, it would be very cool the be able to make relatively accurate slugs (at least within 50 yards) by just using re-purposing super cheap birdshot shells and modifying the Lyman 525 a bit with plastic parts that cost next to nothing. I don't know if it is possible due to the relatively low muzzle velocity the slug starts at. It may be the worst enemy of accuracy is that the slug may become unstable in the trans-sonic region but I am willing to try out my idea.

Anyway, I already modeled the Lyman 525 Slug in Fusion360. Modeling the cap is child's play at this point. I will post some screen grabs of the model and photos of the cap once I get it printed for those interested.

Sure thing, I would definitely be interested in anything you have cooking with the Lyman slug.

[littlejack]

Most of the Lyman slug shooters, fill the cavity with hot glue. Then trim off the excess flat. This works very well keeping the wad from pushing up into the slug cavity. I have about 50 I filled today, and have to trim off.
Very interesting process you have going there.

[pashiner]

The russians make a fullbore version of that slug too. Probably a little heavy for re-stuffing a walmart shell though. Have you considered making the cavity filler a slightly more acute taper than the inside of the slug? This might serve to obturate the skirt, and provide more bearing surface, and a bit more cushion for the pushing. I'd worry about the base wad taking the place of the factory cushion section and possibly upping pressures.

[littlejack]

Years ago, I was experimenting with the Lyman .69 conical in my 12 gauge loads.
It crossed my mind that the base of the boolit needed something to push it Into the rifling upon ignition. Thats the way the hollow cavity was designed, when the black powder exploded under it. Setting the conical in a shot cup was a complete failure. The loads with the .69, shot 1 moa. Thats "minute of brontosaurus"

[littlejack]

Pashiner:
Your comment on the acute taper cavity filler seems like a very valid option.

[mikehill85]

The russians make a fullbore version of that slug too. Probably a little heavy for re-stuffing a walmart shell though. Have you considered making the cavity filler a slightly more acute taper than the inside of the slug? This might serve to obturate the skirt, and provide more bearing surface, and a bit more cushion for the pushing. I'd worry about the base wad taking the place of the factory cushion section and possibly upping pressures.

This is what it currently looks like. You are saying that perhaps I should make the angle on the base a bit more flared outwards to force the skirt open and not extending to bore diameter on the base (pink area)?

[Hogtamer]

i found that soft lead using glue filled base get enought kick in the butt at 1400+ fps to fill bore nicely.

[mikehill85]

FYI, a photo of the parts on the slug, 3D printed in PLA. I plan on printing them in nylon. These are rough since I printed only in and the plastic was too hot but gives you an idea what it looks like.

[mikehill85]

i found that soft lead using glue filled base get enought kick in the butt at 1400+ fps to fill bore nicely.

Thanks for the tip. I would guess whether or not it has enough kick would also be dependent on your powder burn rate as well, no?

[W.R.Buchanan]

This is interesting. How about a two piece Sabot that fits the slug and is about .730 when both halves are together around the slug.

Kind of like this. see pics This is a disassembled Lightfield Slug and these are supposed to be the most accurate slugs out there.

Doing the same thing with the Lyman Slug might work.

Randy

[Markopolo]

Looks like a cap, and a gown... And what would the cap be good for other then bore diam? Are you sure you would need it on the top of the slug like that??? Personally would try it without the cap as well as with the cap. Just wondering is all...

[Hogtamer]

The birdshot shells you're using does have a relatively fast burning powder. 37 gr longshot in a fed gold medal hull (lyman book load calls for up to 39) is a different animal, but with bases filled the base of the wad remains in good shape.

[mikehill85]

You are correct. The only point is to make it bore diameter. I was just trying to ensure that the slug is held in the same orientation whenever it leaves the barrel. Constraining the front and rear of the slug should help ensure that.

Very cool slug design you have there. I was wondering if it is for rifled barrels or is it just air pressure that forces it open when it leaves the barrel.

[littlejack]

The sabot would fall away by design, whether sent from a rifled or smooth bore.
I was wandering, although your 3D design looks good, would there be any chance of the base wedge and cup being dragged off by friction going down the bore?

[longbow]

I am thinking it is easier all around just to cast a bore diameter slug... actually a bit over bore diameter for crush fit would be best. If you have the Lyman mould and a 3D printer and want to play there is nothing wrong with that but I'd suggest making the caps for both ends a snap fit if they are likely to come off in flight. The plastic will get squished some as the slug obturates and if the capped slug is under bore diameter it will rattle down the bore and pound the plastic. If over bore diameter with the plastic of course the plastic will squish some. A snap fit should keep it in place either way.

If you take a look at recovered wads after firing birdshot or slugs they tend to extrude or shear where squeezed. You need a tough plastic and something to keep it in place (back to the snap fit)... I think anyway.

Now that we are onto making slug parts to center the slug in the bore, what sort of tolerances and consistency are you able to get with the 3D printed parts? If it is +/- a couple thou then I'd definitely recommend slugging the bore and making sure the finished parts are a couple thou over bore diameter at the minus end so you are guaranteed a squeeze fit.

And speaking of sabots, could you 3D print a split sabot like the Lightfield slug so the entire slug sits inside a 2 or 3 piece sabot? that might be better than the caps. I think it would be.

My thoughts anyway.

Keep us posted on results please.

Longbow

[mikehill85]

Well I thought the back would stay in place by the pressure at the back and the front would be forced in place by friction. I also planned on using steel wool to rough up the surfaces they are in contact with and super gluing them in place. With the extreme G forces it may not make any difference whatsoever but I thought I’d try it.