3d Printed Shotgun Wads

[littlejack]

I would say, the only real way to find out would be to start making and loading.
But, as Longbow stated, it would be a lot easier to just cast a bore diameter slug.

[mikehill85]

I would say, the only real way to find out would be to start making and loading.
But, as Longbow stated, it would be a lot easier to just cast a bore diameter slug.

Agreed. I will print the current configuration in nylon tomorrow and go to the range on Saturday. I have good data from last week for comparison. If this doesn’t help I will try the Lightfield configuration.

[littlejack]

Looking forward to the results of your labors.

[Cap'n Morgan]

Good luck with your experiments. Tinkering with slugs is FUN!

I have toyed with the idea of using a snap-on wad and ballistic cap (like seen on bottle rockets) on lathe turned steel or brass slugs. Using steel/brass instead of lead would solve the two main problems with lead slugs; Too much weight in full bore slugs and and the tendency of the skirt of hollow base slugs to deform under pressure. While turned slugs probably would be of little interest to the common slug reloader, a cast zinc slug combined with 3-D printed "bore guides" would certainly be possible.

[mikehill85]

Good luck with your experiments. Tinkering with slugs is FUN!

I have toyed with the idea of using a snap-on wad and ballistic cap (like seen on bottle rockets) on lathe turned steel or brass slugs. Using steel/brass instead of lead would solve the two main problems with lead slugs; Too much weight in full bore slugs and and the tendency of the skirt of hollow base slugs to deform under pressure. While turned slugs probably would be of little interest to the common slug reloader, a cast zinc slug combined with 3-D printed "bore guides" would certainly be possible.

Agreed, slugs are a lot of fun. They are probably the most practical projectile for tinkering because of their large size. That ballistic cap you are talking about, was that for drag reduction? I was thinking about this as well. The Lyman 525 in particular must have an abysmal ballistic coefficient due to the flat nose. One would think that adding a more rounded profile would help.
The thing is, you don't want to mess with the center of pressure on these drag stabilized slugs too much (which I may have already done...hopefully not) or they will become unstable. The center of pressure should be behind the center of mass for self-correcting projectiles. Actually you can see the location of the center of mass in the screenshot I posted on page 1. I have CFD software that can calculate the center of pressure, drag, ect. as well. I may get into that as I continue to play around with these designs. Below is a tutorial from that software for those interested. It shows some pretty cool results for the pressure and velocities around the bullet they are modeling.
https://knowledge.autodesk.com/suppo...7B479-htm.html

[mikehill85]

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

I think your idea of snap fit is a a very good one and something I should be able to do fairly easily with a very slight modification to the design. The tolerance on the printer is +- 0.0039 in the xy plane.

I chose nylon for the material because it is an extremely tough high temperature plastic which has great inter-layer adhesion (i.e. bonding between the printed layers) and it is used in so-called self-lubricating parts. The main reason I chose it though is because it is used as the driving band material in Armour-piercing discarding sabot tank rounds such as those used by the M1. I figure if it can survive being fired out of a 120 mm cannon at absurdly high velocities it can withstand a shotgun. The other good property it has is that, while it is firm/strong, it also has some flexibility.

As for the Lightfield sabot, do you have any experience with it? I was trying to determine the mechanism by which it separates, it looks like there are two tabs on either side of the slug which I assume are there to hold it in place on the way down the barrel, once it leaves the barrel I assume the air pressure just splits it open. Of course the pressure was there during the ride down the barrel but it couldn't open because the barrel was in the way. Is that your understanding?

[longbow]

A slug design I have liked and thought about is the Balle Sauvestre:

http://www.sauvestre.com/12-70,1381?lang=fr

Pretty much out of the home tinkerer's domain... until the advent of 3D printing.

Originally I liked the idea of the BRI sabot slug but they reportedly didn't stabilize from smoothbores well. Taofledermaus "proved them wrong" at least in their videos. My thought was to add a tailwad but Balle Sauvestre beat me to that! They have a pretty slick idea that apparently works well.

I have not tried either slug partly because they are hard to get where I am and partly because I am too cheap to pay for factory slugs and because I want to be able to do it myself. Also, I prefer bore size or near bore size slugs rather than a .50 or .60 cal. sabot slug. 12 ga. shotguns are big bore so let's shoot big bore slugs!

Now with 3D printing available some of these things are doable at home for those with 3D printers... you being one of those guys!

Not sure if you have seen BigMrTong's threads:

http://castboolits.gunloads.com/show...in-12g-Shotgun
http://castboolits.gunloads.com/show...stom-Slug-Wads
http://castboolits.gunloads.com/show...-Lee-Slug-Load
http://castboolits.gunloads.com/show...-Slug-Accuracy

He has played with Lee slugs and some home designed slugs using tail wads and sabots all 3D printed.

With the ability to 3D print I'd lean towards a full bore slug with tail wad or a Lightfield type sabot slug near full bore with tailwad. That's just me of course.

I'llbe watching to see what you come up with and field results. It is indeed fun playing with slugs!

Longbow

[mikehill85]

A slug design I have liked and thought about is the Balle Sauvestre:

http://www.sauvestre.com/12-70,1381?lang=fr

Pretty much out of the home tinkerer's domain... until the advent of 3D printing.

Originally I liked the idea of the BRI sabot slug but they reportedly didn't stabilize from smoothbores well. Taofledermaus "proved them wrong" at least in their videos. My thought was to add a tailwad but Balle Sauvestre beat me to that! They have a pretty slick idea that apparently works well.

I have not tried either slug partly because they are hard to get where I am and partly because I am too cheap to pay for factory slugs and because I want to be able to do it myself. Also, I prefer bore size or near bore size slugs rather than a .50 or .60 cal. sabot slug. 12 ga. shotguns are big bore so let's shoot big bore slugs!

Now with 3D printing available some of these things are doable at home for those with 3D printers... you being one of those guys!

Not sure if you have seen BigMrTong's threads:

http://castboolits.gunloads.com/show...in-12g-Shotgun
http://castboolits.gunloads.com/show...stom-Slug-Wads
http://castboolits.gunloads.com/show...-Lee-Slug-Load
http://castboolits.gunloads.com/show...-Slug-Accuracy

He has played with Lee slugs and some home designed slugs using tail wads and sabots all 3D printed.

With the ability to 3D print I'd lean towards a full bore slug with tail wad or a Lightfield type sabot slug near full bore with tailwad. That's just me of course.

I'llbe watching to see what you come up with and field results. It is indeed fun playing with slugs!

Longbow

The Sauvestre slug looks sick. The sabot release mechanism also doesn't require lead tabs like the Lightfield. I'll see how things go this weekend. Perhaps trying to copy the Sauvestre should be next thing I look at.

Thanks for the advice and links. I will keep you posted with results.

[Cap'n Morgan]

Mike, at one point I tinkered with a slug with a large meplat and it shoot alright out to 60 yards after which the groups would cease to be groups:

http://castboolits.gunloads.com/show...=1#post3408361

[longbow]

Cap'n Morgan:

Back to the "form" comments I made in another thread.

You seem to have a pretty good handle on slug design so I'll ask here:

What's your take on nose shape affecting flight/aerodynamics?

turbo1889 said the Lyman sabot slug with its big meplat becomes unstable at transonic velocity. I have no personal experience with it but because wadcutter boolits have that reputation I can believe it. Same would apply to many other slug designs with very large meplats like the ACE 740 gr.

I have to think that the large meplat exaggerates the blanket effect that Randy brought up and that a more streamlined nose shape of hemispherical, pointy like the Moose .69 Minie or SWC like would be more streamlined providing somewhat better BC and less blanket effect plus if the slug tips in flight the nose would have less drag than the skirt so better self correction.

I always wondered why Lyman didn't use a nose shape more like the Rapine slugs with TC nose. Personally I think it would have been better ~ talking for smoothbore here all the way.

Maybe our OP could 3D print a TC snap on nose for testing (hint, hint). It wouldn't add much weight (probably a good thing) and wouldn't help with moving CG forward but would make a more streamlined projectile.

Kinda thinking a profile like:

https://www.pyramydair.com/s/p/Crosm...nted_175ct/111

pointy but with a smallish meplat (nose pour anyway).

Longbow

[longbow]

By the way, I note your Brenneke slug in that thread that shot well for you has a quite large extended nose on it seemingly bigger than original Brenneke's. It worked very well. So now I have to ask why you didn't stick to that design?

And back on track something else the OP might experiment with is adding both "nose cone" and extended tail wad to his Lyman sabot slugs. Kind of a combination of BigMrTong's tail wad, extended nose cone and full bore slug all at once... but here I go trying to influence someone else's design. Just my thoughts and comments you can use or discard as you see fit.

I'll shut up now.

Longbow

[mikehill85]

Mike, at one point I tinkered with a slug with a large meplat and it shoot alright out to 60 yards after which the groups would cease to be groups:

http://castboolits.gunloads.com/show...=1#post3408361

Impressive results and good shooting. It definitely seems that once these types of slugs get to further distances and therefore lower velocities they start tumbling. It makes sense because they are drag stabilized and the loss of velocity means they can no longer self correct. Having a long tail like some Plumbata style slugs helps with this by moving the center of pressure further away from the center of gravity of the projectile. You're still losing drag at lower velocities but your center of pressure is further away to start with. At that point the issue becomes ensuring the tail stays attached and always exits the barrel in a similar shape.

Have you heard good things about the accuracy of the Sauvestre style slugs?

[mikehill85]

By the way, I note your Brenneke slug in that thread that shot well for you has a quite large extended nose on it seemingly bigger than original Brenneke's. It worked very well. So now I have to ask why you didn't stick to that design?

And back on track something else the OP might experiment with is adding both "nose cone" and extended tail wad to his Lyman sabot slugs. Kind of a combination of BigMrTong's tail wad, extended nose cone and full bore slug all at once... but here I go trying to influence someone else's design. Just my thoughts and comments you can use or discard as you see fit.

I'll shut up now.

Longbow

Long bow, I think those are very good ideas and actually things I had thought of as well. I asked for input and I'm glad we're thinking on the same lines. If the flat caps stay on I will definitely look at doing something like this.
The very flat nose of the Lyman 525 seems like it is begging to have a terrible ballistics coefficient. In the Lyman 525 slugs the large amount of weight at the front pulls the center of gravity forward and the flat bottom creates a vacuum that stabilizes the round. Adding a tail, even a flat disk tail should help to stabilize it at lower velocities.

I would guess that they may have designed it with a flat nose because they wanted the driving bands to be relatively close to bore diameter and didn't want to make the round preposterously heavy. It is already a pretty heavy slug as it is. When you think about it, the only way they could keep the overall mass the same and add more in the front would be to reduce the thickness of the skirt which they probably kept pretty thick on purpose to allow for safe obturation across a variety of loads and if the mass were too much higher than it is now it probably couldn't be used in shotcups as intended without crushing them into nothing.

Lol. If the slug gets anymore plastic modifications to its outward appearance it is going to become a Kardashian.

[Cap'n Morgan]

Cap'n Morgan:

Back to the "form" comments I made in another thread.

You seem to have a pretty good handle on slug design so I'll ask here:

What's your take on nose shape affecting flight/aerodynamics?

Longbow. Until I saw this picture below, I believed the more "pointy" the better. However, that is NOT the case when we're talking subsonic speed/drag. The most drag is produced by an open cylinder (1.0) and the least by an ordinary hemisphere (0.01) Interesting, a pointed 60 included angle has more drag (0.2) than the traditional ogive shape we find in boolits (0.05). I'll gladly admit that these numbers go against my first intuition and I do not know how these different shape values would affect the actual ballistic coefficient figure of the slug , but there you are...

[W.R.Buchanan]

I think the whole point of the Lyman Slug is to give the home loader a slug that will be relatively accurate out to 50 or so yards and have serious knock down power. You know the flat nose is going to dump all it's energy very quickly, which for short range hunting would probably be the best thing you could ask for.

The Idea of the snap on nose piece and tail piece to bring it up to full bore size I think has merit in a Rifled barrel. I don't see any advantage from a smoothbore simply because you can duplicate the square launch with correct wads and nitro cards etc. Once the slug leaves the barrel the caps are going to disengage quickly from either a smooth or rifled barrel.

Won't know for sure until you try.

Randy

[Markopolo]

I am watching for results as well...

Of course I watch all these investigative shotgun slug threads. Better then reality shows any day...

[longbow]

Now then Marko you are laughing with us not at us right...? I hope so anyway!

Cap'n Morgan:

I can't argue the fluid dynamics but with shotgun slugs or boolits the conditions are varying along the flight path and BC changes with velocity as well as shape. A "projectile" in a steady flowing fluid stream of liquid or gas is in steady state condition where our slugs/boolits start out relatively fast then slow along the trajectory and shotgun slugs normally start out supersonic but somewhere around 50 yards or a little past, depending on starting velocity, they go transonic.

Also, the blunt shapes are better for subsonic velocities than pointy shapes. Some people load pointy boattail "J" bullets backwards for subsonic use for that reason. At supersonic velocity pointy boattail bullets are best shot point forwards.

Wadcutter boolits do not maintain stability over long range so I have to think that Lyman sabot slugs with their huge meplat are probably suffering from the same issue. I do remember turbo1889 saying that they become unstable at transonic velocity. Maybe if launched subsonic it isn't an issue. I do not have a Lyman mould so no personal experience there.

A hemispherical nose or RNFP with moderate meplat makes sense to me.

Also, I am not as concerned about BC as I am about drag on the body and skirt where in reality the more drag we get likely the better off we are so contrary to goo BC but good for self correcting drag. As Randy says, our shotgun slugs are short range projectiles so high BC is not really much of a plus. If I can get good accuracy to 100 or maybe 125 yards I'd be a happy guy and BC at that range isn't going to have a huge effect on trajectory. Let's face it, the Lyman slugs are proven out to 100 yards or better so if they can maintain lethal energy and acceptable trajectory then anything better is a bonus.

My understanding is that at supersonic velocity the shockwave moves back to the tail end but as the slug goes transonic the shockwave starts moving back up the body to the nose and there is a lot of turbulence going on at that point. I should do some reading I guess as I have very limited knowledge in that area.

Longbow

[Markopolo]

Are you kidding?? I love this stuff.. Never laffing at!... always learning and listing to what the real experts around here have to say. Sadly, I am Not one of the experts, but seek to glean whatever I can with my pea sized brain... I have fueled many experiments based on what I have seen and learned here... that is what I mean when I say, way better then reality shows.. what the heck can any learn from watching those???

[longbow]

That makes me feel better! I am a sensitive lad don't you know! Yes, lots to learn here... and the learning just keeps on going it seems. Lots of new young guys with shiny brains stepping in and showing new stuff too. It is all good fun and a great bunch of people here sharing and learning. Good stuff!

Longbow

[W.R.Buchanan]

LB: Have you started your "Tactical Training" yet? I want to hear frequent updates on how the gun handling is going.

I have to tell you that after learning how to run a Pump Gun fairly well, that the A5 transition came quickly. I was up to speed with that gun before the morning was over with on the first day of the class. Most all of what is covered in the book directly translates to the A5 other than not needing to port load it because of the Speed Feed Feature. But you can port load it as well.

You can learn most of this at home by Dry Practicing. Which you'll notice it says right on the cover. "Dry Practice Manual!"

Have fun this weekend er I guess you guys don't do Memorial Day up there, huh?

Randy