Shooting 3D Printed APFSDS Tank Rounds 

The finned dart sabot rounds have been some of the most difficult things for me to get to work and I'm dealing with half the scale you are. You can't put a wad behind the fins because that will just crush the fins. The sabots double as the gas seal. Most of the darts we have tested (CanaDart, Anferov bullet, Dynaslug, and Sauvestre) have lugs on the shaft that match up with lugs on the sabots. Almost all the pressure acts on the sabots and pulls the dart down the barrel as the dart is locked onto the sabots. A common failure was when we tried to push the rounds too hard - it stripped the lugs right off and the sabots went flying at a high speed and the dart followed along at a very low velocity. The video we just did with the CanaDarts used very brittle 3d printed parts. I had to use a small 25 grain charge of Pyrodex and a spoonful of coffee as an inert buffer to fill the space. They worked OK but we were only getting about 500 to 600 fps.

Your problem is simple, the sabot is supposed to lock on to the penetrator and is used to accelerate the penetrator down the barrel with the sabot releasing and flying free once the penetrator exits the barrel. Your base was is crushing the stabilizing fins upon ignition.

Your biggest problem right now is your APFSDS projectile is getting left behind by the sabots because there's nothing really holding them together. Real APFSDS rounds are held mechanically to the sabot by a series of machined grooves in the sabot and projectile locking them together. The sabot has the majority of the surface area and is where the majority of the "push" from the gunpowder goes and it pulls the APFSDS projectile down the barrel along with it. What might work best in your case is to make the metal rod go down to the base of the fins and have an additional base to push the projectile from behind. That way the majority of the force is the new base pushing on the rod from behind instead of trying to pull the rod from the front. You would have to redesign your sabot a little to make sure it could also hold up to getting pushed from behind, but that should be mostly making the rear section thicker. You could also try printing your fins thicker and from Carbon Fiber TPU, which is significantly tougher against sudden shock and impacts while still being pretty stiff. It's pretty abrasive on brass nozzles so you would need to get at least a hardened steel nozzle.

1. Don't make pressure push on the fins with the pad 2. add grooves on the rod so the sabots have tight grip 3. Add aerodynamic surfaces on the front of sabots that will better push them apart after leaving barrel - I really like your creativity 🙂

Taufladermaus did a video like last week shooting some flechette rounds. It seemed like the sabot fully encased the flechette and had a cup shape at the tip above the tip of the projectile so once it's out of the barrel it catches air and splits instantly. I feel like that would work well here.

Oh man, a collab between this channel and Kentucky Ballistics would be amazing

On APFSDS, dart shaft's positive ribbed while Sabots' interior's negative ribbed so the sabot grips the dart shaft and doesn't blow out. Current construction is a soft "rubber gas check" then delicate plastic fins, then metal dart. On firing, the rubber and plastic fins probably give some or shatter. Maybe rag packing over powder then a short wood cylinder behind the dart as a rigid pressure bearing point. The solid shaft should carry all the way back to the bearing point - wood dowel -( the fins should end at the back of the dart). The sabots look sound, they only need center the dart, elastics alone should do. ..just a idea... besides, wood is cheap ! ..cheaper...

Several people have made one suggestion of cupping the front flange as an air catch when it leaves the barrel the air will catch the fina pulling them away from the penetrator. But the biggest thing for stability is not using a pusher behind the penetrator. The sabot needs to pull the core out of the barrel. This is because without a perfectly balanced core any slight instability is amplified by the pusher. One of the easiest ways to get the sabot to lock in to the core is cut a small groove around the shaft of the penetrator. The with the sabot add a small lip on the inner diameter to fit into the groove.

You're definitely crushing the fins. Either metal fins or having the rod go right through to the back would be the quick and dirty solution.

Never would have I imagined seeing an old canon, be fitted with an APFSDS round 😅

1) I'd try a different 3d printed material- I've used PETG sabot rounds in my muzzleloader, they don't seem to break up at all (less brittle) 2) I'd try a softer wad- maybe felt layered or t-shirts layered 3) That penetrator needs to be nose-heavy and tail-light. The first 1/4-1/3 of the penetrator should be lead or steel, the body should be composite, and the fins 3D printed Love this channel dude, keep up the great work! I hope these suggestions make it to you!

"My name is Jonathan, this is my canon." Your intro have no right to go this hard

Don't put wadding of any kind behind the fins, that's only going to load them and destroy them. Serrate the penetrator and have the sabot grip the serrations to pull it through. If spacing and a smaller charge doesn't help then you'll have to go with an all metal dart. Normally the fins are in the propellant explosion, they are NEVER pushed.

I see good comments here. Mainly I would just make the discarding part of it a chunky cylinder that fills the bore and encapsulates the fins in addition to the penetrator to support everything as well as possible. 3D printing lends itself to chunky designs and your fins are too flimsy to be carrying all that acceleration by themselves. You might even see about adding a steel cross pin into the penetrator a little further up that can also key into the discarding sabot to take some of the stress off the fins. This would allow the sabot to pull directly on the penetrator taking some of the force away from the back. I imagine that even if the fins are surviving, the penetrator is getting driven back through the fins and through your TPU pushers like the penetrator that it is lol

Thank you guys so much for all your wonderful ideas on how to improve this round! We will get this working in the future with all of your improvements. Thanks for your support!

This sounds like an AK-50 style project that will become the core of the channel and will be solved in like 10 years xD

Name the Segment “You Cannon not be serious”

steel fins welded might help and mayby an aluminium bore sabot. Cool stuff.

Theres alot of good information in the comments to recap the main changes that you need to make if you want this to work 1. you cannot pit wadding behind the fins bc the fins cannot be made strong enough to be load bearing and will be crushed by the wadding 2. In a normal sabot round the petals interlock with grooves on the projectile and the petals are responsible for pulling the projectile down the barrel and obturating the barrel (thus taking the load of the fragile fine) Also a note on terminology, what you refer to as the "petals" the parts the hold the projectile are called the "sabot", and the part you refer to as the "sabot" is the projectile

Hah! You beat me to it! I've been itching to turn some custom tank sabot penetrator rounds for one of my cannons.

We now have "Taufladermaus" style content but with a Friggin' Cannon!! Sweet!!

For old school artillery, you need old school ammunition. Forget the 3D printed fins, just make a nice penetrator spike and fit it with a suitable discarding sabot. Bore a hole through the end of the spike and tie some hemp line with a monkey fist ball knot made a few thousandths shy of diameter of the barrel. Leave about 4 - 6 inches of line between the spike and the knot. Soak the line in water over night, this will keep it from combusting when fired. Ensure the monkey fist knot is still about the same size as the sabot outside diameter, dry it out a little if its swelled with water, coil the line to butt the knot up to the sabot then load the lot with a wad to keep the monkey fist off the powder. The ball should trail on the line when fired, inducing drag and stabilizing your penetrator. With some fine tuning on the size and weight of the rope ball, you should be successful.

I would also recommend finding the center of gravity of the dart too. You can do this by measuring the length of the dart and then suspending the dart by a single string at the measured center of the dart. Make sure you start with more length at first so you can cut it into the right length as needed. Do this properly and you’ll eliminate all tumbling after the dart leaves the muzzle.

I don't care if your sabots failed, I instantly subscribed because of how you asked for feedback on how to get better. Keep it up dude!!!

OH YEAH jsyk, real APFSDS rounds have ledges / steps on the penetrator that interface with some on the sabot, so the sabot actually drives the central projectile. here, the sabot may just slide off the penetrator during firing as there is no mechanical interface

Coffee grounds are a good space filler for some of this stuff too

That baseplate disc is transferring the entire pressure load of the black powder charge to the fin assembly, and the damage is multiplied by the difference in weight between the fins and the metal penetrator. What I would do to redesign this is modify the baseplate and fin assy to where the baseplate disc can support the pressure load and transfer it directly to the penetrator rod, which seems to be the most difficult object to get up to speed quickly. The disc can be done away with entirely, however, if you cut a ribbed pattern into the penetrator rod and a matching one into the inside of the sabot so it can "grip" the sub-caliber round itself and so that the pressure load is dispersed into the sabot, which drags the penetrator and fins along with as it travels out of the barrel. You might also want to toy with the size of the powder charge. Too much powder means too high of a pressure spike, which means the sabot or baseplate disc would be more likely to shatter under the strain of such a sudden acceleration. I hope this advice is good enough to make a difference, preferably for the better.

Idea: Simply move the fins forward on the penetrator so that the very rear of the penetrator itself is what has the pressure from the pad instead of the fins. This will be the simplest way to resolve the issue with minimal modifications.

There's another guy on youtube called flasutie id hit him up and ask him for ideas since it's one of his specialties and he might be able to help i hope you get it to work and i can't wait for the next video.

Watermelon. Beautiful.

As much as we love 3D printed projectiles, they have limits as far as surviving violent acceleration as you would see in a black powder cannon. It's not impossible, but requires additional design improvements to prevent the projectile from being obliterated to avoid the plastic from being destroyed during firing.

I am all for this, and best of luck to this young man and look forward to seeing his videos in the future.

The sabot of the round itself is suppossed to be exposed to the pressure gasses, not a baseplate behind the round. the fins were clearly not strong enough to hold all the force. The problem with your round is that the sabot will get launched out without the dart if you had no baseplate. To fix that you need grooves on the dart and the sabot so they get locked together while still in the barrel.

If you look at the tank's APFSDS, it's the back "bulge/ring" of the sabot that seals the case and is pushed by expanding gases (the front one keeps penetrator straight). The fins are actually inside the propellant when loaded. I think in your case those TPU disks simply push through stripping fins, because the penetrator is not supported well enough. Maybe redesigning the sabot in a way that it is pushed directly (so the sealing bulge/ring is behind the fins), and adding on the inside something that would grip the penetrator along its length would help. Anyway - great video.

excited to see what you and the community get up to with this!!!

early sabot projectiles used tapered sabots to act as a way of holding and pushing the projectile down the barrel

You might try TIG welding some steel fins onto your penetrators. You might need a jig to hold the fins in place wile you weld though, to keep the heat from warping them out of alignment.

Almost 5000 subscriptions! Keep it up man. You cannot have enough cannon content

Fascinating, keep up the good work

Bring the base of the steel to the base of the fins... Don't allow the fins to be pushed along the rod.

Failure is always a welcome option. Looking forward to the next set of tests.

Im 51 and the kid in me comes out watching someone firing different projectiles at targets . Whether they fire well or break up the explosion and smoke are enough for a smile 😃 😊 im a simple person 😅

Weld the fins on the rod.

PLA is too brittle.

Hey, I just wanted to mention how awesome it is to see your channel blow up recently. Keep up the great work!

You guys doing gods work.

I dont think the 3D printed fins are going to hold up to the forces involved. An alternative design would be a yo-yo style to generate the spin. Sounding rockets use a yoyo to despin, but a modified design could also spin up the projectile. There are two ways. The first design is simpler, you attach a wire to the Sabot petals and spool the wire around the projectile. As the petals are flung outwards, they unwrap from the projectile, spinning it up. The second way would be harder but more similar to rocket designs, you would need to have some small weights on the end of wires with a slight rotation already present, if the wires are winched inwards to bring the weights closer to the projectile, the moment of inertia will decrease and the projectile will exponentially increase in rotational speed to keep the angular momentum constant. Having the wires pass through holes in the projectile and anchored back to the cannon or the sabot could winch the wires inwards if done right, the other ends of the wires just having some weights attached to them. The best way to think of this second idea is a figure skater pulling their arms in to spin very fast, the same principle will apply to the sabot if you can pull mass inwards to the center of rotation somehow.

a few things I see that can be improved: first APFSDS Penetrators and the Sabot have some sort of grooves that basically are supposed to do what you did at the end with the rubber band as well as giving the sabot enough friction the keep them on the penetrator before firing , second: you souldn't strip the sabot parts together to allow them to seperate easily after leaving the muzzle, and third: dont use that base plate at the back. you basically replace the actual sabot with that thing, which causes a lot of issues. Probably it also would help to try a material with a slightly better durability like ABS instead of the PLA.

Just a thought. If the casing were to not only cover the middle but wrap along the bottom of the fins for more grip that could encourage more of a solid shot. Once the back is out of the cannon there would be the air that could separate the shells and also potentially saving the fins. My biggest suggestion is to have metal fins. You either need to weld medal fins to the bottom of your rods. You can cast them in sand. But you really need to try to keep a total of 4 pieces. The 3 pieces for the shell, and the single stabilized rod.

Cylinder of balsa split lengthwise. Short small fins that taper flush after 25 % or so of the length of the penetrator. A couple of right triangle gripping grooves forward of the fins. And a minimal amount of Elmer's glue to hold everything together for a couple of yards past the muzzle. A potato cannon bestowed this knowledge upon me many moons ago and it yielded great results after some fine tuning!

That first one would create a nasty bruise. Omg I love this!

Try using a stabilizing cone instead of fins. Tank training ammunition is cone-stabilized rather than fin-stabilized. Without machining the penetrator to lock onto the sabot petals, that might be the most durability you can get out of this design. Also, ensure that your rear TPU disk ("wad"?) is applying pressure directly to the metal rod, and not the cone or fin stack. Mounting the cone or fins a bit forward of the base of the penetrator will help ensure that the bulk of the force is absorbed by the metal rod and not the printed part, which should leave aerodynamic forces after the round leaves the blast envelope as the only thing the printed part needs to withstand.

seen a lot of people saying this, but it's true. this dude really is the taofledermaus of cannons

There are a lot of ways to make this work on your cannon, depending on what kind of materials and techniques you have at your disposal. for starters, as a lot of other people have pointed out, the TPU plug in this configuration is never going to work, not only because youre pushing the fins, which are certainly going to shatter no matter what plastic you use (even aluminium might be destroyed), but also because the TPU is undoubtedly going to be perforated by the rod unless you make it unreasonably thick. An easy fix to this would be to make the rod go all the way to the rear of the projectile and using a metal plate in front of the plug, then the design of the sabot would have to change to also touch that plate such that the fins dont get shoved into them upon firing. another observation would be to remove everything holding the sabot together, perhaps some white glue can be used to simply hold everything in place, with the idea that it will immediately break apart by the shock of firing, since you definitely dont want the sabot to remain attached to the projectile. A slightly more complicated solution can be found by trying to more closely mimic the way a real apfsds round works. by grinding/machining grooves along the penetrator and designing matching grooves on the printed sabot (ive seen threaded rods suggested, altho its an easy source of something with grooves out of the box, im not entirely sure if the features are large enough for the plastic to hold onto). depending on how weak the plastic turns out to be, those features might just strip off so youd have to use some kind of metallic insert on the sabot (im honestly not sure how youd go about doing that, maybe some steel sheets could be cut in the same cross section as the sabot and then glued on both sides of each petal (petal being the name of each segment of the sabot), and the printed part would obv have to be altered to make sure everything still fits in the barrel snugly and without gaps, perhaps the steel plate could be smaller than and inset into the print to avoid steel on steel contact in the barrel and make sure there are no air leaks (it would be rather difficult to make the flat sheet seal properly)). The final overkill solution would be to make everything out of metal, with the steel penetrator and cast aluminium fins and sabot. with the previous solution there would be nothing protecting the plastic fins from the heat of the explosion so that might fail even if it doesnt get contacted by anything solid, either by melting or shattering, so if a better suited plastic isnt available metal might be the only way. to that end, id recommend lost wax casting, as that allows for the most detailed parts and shouldnt be terribly complicated, altho simple sand casting can certainly work with a lot of post processing. the fins can either be directly cast onto the steel rod (not 100% sure if it would work) or attached later, either screwed or press fit/glued on (obv only go with screwing if pressing fails). youre likely to need help with either process so id maybe try to find a local place that does casting.i certainly hope i doesnt come to this because working with metal casting is quite time consuming and dangerous. Some final considerations as far as the general design goes: >as i said at the beginning avoid holding the sabot petals with anything that could resist the firing process, like tape and rubber bands. altho they might tear apart its also possible they dont at all, too late or in an inconsistent manner, which could mean it messes with the flight path of the dart; >the design of the petals can be changed significantly. this version that tries to mimic the appearance of the real one would probably only work in metal, with the plastic versions having to be significantly thicker to provide enough structural stability and strength. the real darts are designed in the way you see for several reasons: they need to be light (you dont want to waste the energy accelerating something that isnt the projectile), the contact patch in the barrel has to be minimal to reduce friction (the only contact is the seal at the back, which prevents the gases from escaping, and the piece at the front, which serves double duty as something to stabilize the projectile inside the barrel and to scoop the air after it leaves the barrel to ensure the petals release consistently and cleanly), it needs to leave space for the propellant charge (look up images of a complete tank round and youll see how the projectile sits very far into the casing), it needs to separate early and easily from the rod (this is accomplished by the aforementioned scoop). all of this means that if you dont need the utmost efficiency, several of those design considerations can be ignored and you end up with basically a segmented cylinder with a hole for the rod the pass through (and ofc the internal features to hold the rod plus whatever modification would be needed to accomplish this). some extra features that might help would be a taper in the rear (similar to the real one, altho less extreme), which would help squeeze the sabot into the rod by the pressure of the explosion (force vectors and all that), and the scoop at the front to help with the sabot release. Finally, im just an idiot with a keyboard on the internet, so, altho i wrote as if everything was factual, do take this wall of text with a grain of salt (this was by no means an exhaustive list of everything that could be done nor guaranteed to be correct).

Awesome video. 👏

That's... something I didn't expect, but YT suggested your channel! You get my sub and like, cause I like cannons. Cheers!

It seems like the main issue is the power of the Canon is pushing the fins of the Sabo through the shaft basically destroying the fins before it's even leaving the barrel to fix this it would be better for the shaft of the Sabo to go all the way through the fins

Food for thought... The APFSDS has grooves which lock it into the sabot. Maybe if you turned a few grooves into the rod, or use a peice of allthread, it may adhere better to the sabot. Also, you need a pushing charge, not a forcing charge. Perhaps loading your cannon to the training load specs might change the pressure dynamic. 😉 And yes, pin the fins. They want for a mechanical connection to the rod.

I did 10 years in the army, and worked with munitions multiple times. What you need is a base that is the bore diameter, with a 3-4 part cast that fits around the projectile that us the bore diameter on the outside, and patches the projectile profile on the inside.

Our founders are smiling upon this video, shedding a tear of happiness.

Pretty cool video dude, I would like a second part

Thats a great start!

There’s several amazing collabs which come to mind

The sabot is supposed to be the thing that absorb the energy. Make groves and sabot with groves to propel the dart. Also, use a 2 piece sabot with a air drag that would split it apart when it is on the air.

There's a reason APFSDS rounds witbout the sabot have ridges running down their length. It allows a large surface area for the discarding portion to grab onto. Great video btw, never thought I'd see APFSDS fired from black cannon gun 😂 I subbed

Hell yeah! This is awesome

The sabot must be metal. Let me explain. If you look at the m1 abrams, the whole entire system doesn’t have any buffers between the shell and the casing. The sabot must also be metal if the projectile is metal, that way the cannon pressure wont make the projectile sheer off any metal holding the projectile in place. I recommend CNC aluminum, it should be strong enough, plus you can print it into whatever you want. Edit: if not already, it should be properly held together on the inside. That way the projectile cant move forward or backward in the sabot, so then the sabot can cleanly release after the cannon fires and it has left the barrel.

You need to create break groves and only have the thinnest pieces of material holding them together. The tape & bands are flexible and do not break apart. You need to guide the break apart and weaken the material along those break up sections so the force of the wind is stronger and more than enough to break the material. You’d better off using a more brittle material like dried cardboard or very brittle plaster. You’re not using even close the power of a shot real sabots experience when fired so you need to compensate by using material that’s more brittle to get the proper break away affect you’re after

Grape shot+multiple cannons+ flatbed truck= land pirates!

Okay, couple things I noticed. First of all, when you load the dart, your ramrod actually pushes the dart back inside the sabot, meaning that during firing, the fins and wad slam into the sabot and probably shatter everything. Try to put some grooves into the penetrator dart that are matched by the sabot to keep them together. Second: the material. Sabots are made out of durable materials to withstand the stresses of firing...yours aren't. There's probably not much you can do there as I don't know what your 3D printer can take, but maybe you need to design it with some strengthening ribs to keep it together more. Keep in mind it would still be a sabot if it didn't have the design of a modern tank one. Try a blank cylinder that has a cutout for the fins at the back.

While I'm not sure how the sabot works, I am positive that the needle and the fins should be one element. If the needle doesn't have fins, it won't be able to fly a straight and stabilised path, so for this part I would just weld metal fins to the needle.

Just sayin. I love this experiment. Definitely keep at it till you get it so we are ready to fend off enemies with black powder

Hey, it´s a great project but here is the thing, the pressure in the barrel goes through and around the Tpu wad, although it has a good seal, which causes the sabots to fly off the penetrator, which then can not be stabilized and just spins through the air. Also somewhere in the process, it shears off the fins. I would say try making the fins thicker and maybe try printing some ring that you can secure on the penetrator, that will ensure that the sabot does not fly off.

Hi, Just an idea that I have seen: Use a length of all-thread rod as the penetrator. You can then use a thread to locate the sabots and lock them to the rod. The gas seal is then on the sabot.

you popped up on my homepage out of nowhere... I see cannon.. i see big poof.. i watch.. i like.. me happy

Move the centre of mass towards front of the round. You can do it by providing draft angle to penetrating dart. Also increase the cup depth of seperator with through holes at each.

I never thought about it, but a scary aspect of war during the time of cannons I noticed how you said the smell of watermelons in the air, and it made me think of the fact of if it was a human a horrible thought, but I wonder what that smells like and I’m sure that smell would probably triggered PTSD to war veterans 😮

good new format. well done. I like the taufledermaus approach. a you-make-it-i-shoot-it type thing will be really cool to see. some of their makers might even try remaking some wild rounds from the past but bigger. as for the fins. nylon or maybe something more squishy like tpu flex might be a good idea.. also something soft like cotton or cardboard between the pusher and the back of the fins.

I do like guns but i didnt know that i like antique cannons this much since i found your channel

Great job in editing in some VO on the editing style. More dynamic, for sure.

If you keep your original sabot design but lengthen it to encase your fins with the penetrater lengthened to be slightly past the back of the fins to rest on the sabot it will protect the fins. Also adding a slight concave to the front of the sabot may help with separation. Using a heat resistant paint on the cracks will hold the sabot together but is fragile enough to break for separation.

Someone beat me to the comment but i'll add my knowledge anyway. The ridges on APFSDS rounds are there to lock the sabot to the projectile. Without it the pedals wont separate correctly outside the barrel and the sabot will leave the barrel before the projectile. This should be a relatively easy thing to fix. With a relatively lower pressure gun like a black powder cannon, having the sabot be passively held together with no rubber bands or a weaker rubber band might work better to ensure the sabot seperates

I love the concept

The PLA fins are never going to stand up to pushing that rod out the barrel; extend the rod all the way to the pusher plate, make the pusher [wad] out of a more rigid material [nylon perhaps] than TPU and then attach the fins to the rod. If you use threaded rod, you can screw a nut on near the front that will provide a rigid drive interface for the discarding sabot, and all thread is common and cheap.

Very cool man good work😊

good stuff, hope your channel blows up (no pun intended hahah!)

I'm copying some comments here, but I see a solution. Loose the base plate, don't push on the fins. Firmly secure the sabot to the penetrator, and let the whole things go down range. The penetrator will penetrate while the sabot shatters!

Cool channel, glad the algo put it infront of me.

Early APFSDS rounds used aluminum sabots for Al's lightness and rigidity. Might be worth a shot. Backyard aluminum casting's pretty easy (don't breathe the fumes or spatter metal on moist concrete!) and you can use 3D printed sabots to make sand molds.

Ditch the fins, use a solid cone 30-40 degree angle. Need to turn grooves into the shaft and have matching grooves in the petals. Lastly the front and rear petal supports need to be further apart to improve the stability

Yoh, I always think of using an APSFDS on a medieval cannon , see if the round will increase the cannons effectiveness. You did us a good service for this video 😎👍🇺🇸

LOVE the smell of watermelon. You've created an outdoor air freshener. Looking forward to future vids. Thank's so much for posting.

I see some mechanical problems with your dart and sabot design, this might solve that: 1. The dart should go all the way through the fins to the other side and maybe even have a bit of an extra length to it to interact with the plug. That should reduce loading on the fins. 2. Maybe use threaded rod? Get a threaded rod, then tap the same thread in to the sabot. Should allow for nice, even spread of load. 3. The sabot should go back around the fins and close behind the dart only leaving the metal rod in the back exposed to take some of the load off the fins. 4. To prevent Newton's cradle effect, you need to slow down the initial acceleration of the projectile. Some cushion, like thick layer of cardboard, or cork, or rags, or a combination should do. If this doesn't work, you may have to go for sturdier materials. Like an aluminium fin or even welded sheet metal to act as fins. The sabot is really kind of secondary and might as well disintegrate once it leaves the barrel. Maybe it would be cheaper and faster for you to pack a paper tube with more paper and have the dart in the middle of it. At least until you can get the dart to stay in one piece after firing.

I'm seeing a couple of major design flaws already 1. Adding the base plate is creating more problems than it's solving there should be as little stress as possible on the fins during firing because any damage to them will screw up your accuracy. 2. Your sabot should be mechanically locked into your fin round until it leaves the barrel either through a series of matching grooves and ridges or a flange at the front this will put all the stresses on the sabot during firing preventing damage to the projectile. 3. If the font of the sabot forms a concave cup to catch air and the forward binding is weakened enough this will cause the sabot to open properly and give it leverage to snap the rear binding causing a cleaner separation. 4. Depending on how your sabot is handling the stress of firing you may need to make it much more substantial and or switch to a more elastic less brittle material.

The puck at the end pushes on the fin which is in turn unable to transfer the huge force to the penetrator. The fin is crushed, the gases mostly escape, hence the relatively low speed compared to the cannon ball. I suggest sticking the penetrator *through* the fins, so the puck pushes on the steel rod rather than the plastic fin.

First video of yours I saw I was like: " wow, here's another dude with some weird-ass hobby on youtube". Now every video of yours I am like: "WOW HERE IS THE DUDE WITH THE CANNON!". Subscribed.

Extend the petals behind the fins, or just braze/weld on some metal fins. Military designs have gripping feature inside the petals that lock into the penetrator.

Really nice video quality with 4k hdr!

So I'm 12 days late. But I immediately noticed one thing. From what I've seen modern APFSDS round the penetrator has like a backwards groove to them. As others have commented, I assume this is do that the discarding portion of the round more so drags the penetrator along the barrel rather than the penetrator pushing the entire round down range. Might explain the fins reaching the target first before the main bit is even half way.

OMG you actually did it, amazing! sad that they didn't work. maybe having metal fins welded to the penatrator would work? Also nice voice over and always great camera work. If you get the APFSDS rounds to work ill send you a nice bottle of Dutch liqueur!