Fin stabilized projectiles

[Elkins45]

There used to be a thread on this site somewhere started by a very talented machinist who made all sorts of wild custom molds. I remember one was a Phillips head screwdriver, one a soft serve ice cream twist cone and other nutty stuff like that. They were extremely cool but certainly not practical. I found the old thread but the pictures are all gone.

Fast forward to 2018 when a company called Franklin Armory thumbed their noses at the NFA by releasing an AR with an 11” barrel that isn’t an SBR by using a barrel with straight grooves. That makes it technically not a rifle. One of the things they promise is that they are going to sell fin stabilized projectile ammo in 300 Blackout to go with it.



It would be fun to have a mold to pour something like this from lead. I haven’t seen anything similar other than the novelty molds I mentioned. Is this something anyone here has experimented with?

[OS OK]

If I weren't such a FUDD perhaps I could help you out here, I sorta remember those profiles too...this is all I could find.

http://photobucket.com/gallery/user/...MTM1OQ==/?ref=

[slim1836]

Old Para was his name if memory serves me correct.

Slim

[OS OK]

Yup...'oldpara'

prolly one guy has the photos...jmorris in post #452

http://castboolits.gunloads.com/show...-anyone/page23

[country gent]

4 fins would be doable but would be a job to cut. I believe I would make it a nose pour cutting the front body in, then mill indicate in and cut the fins. fins would probably need 1 1/2* -2* release angle on them to allow easy drops and not pulling fins off. My concerns with the design is how well the fins will hold up to pressure and acceleration when cast of lead, and with the ogive base how bad blow by is going to be

[bmortell]

Everything ive seen on fin stabalised projectiles were tested in shotguns, and it pretty much always either breaks from the wading pushing on the fins or just tumbles anyway and would of been more accurate without fins. But this is different since its being pushed from pressure on the body instead of the fins.

Im no rocket scientest but im not sure the fins would actually be guiding air at 1kfps or so, i think the air would be making a cone around it and stability would come from the front half weighing more than the back half. If this were made of lead g forces on launch would be wanting to strectch the fins back or break it off since it seals in the front its basically pulling away from stationary fins. To counter that youd need a thicker center stem and fins but the more you do that the more you mess up the balance and it may tumble.

Im unsure if lead has the physical strength to work and copper would be much easier function wise. If you ask me youd be better off with just shooting a hollow base shape thats stable with no spin like many shotgun slugs and pellets. But im just a random moron so this might be useless

[Elkins45]

Everything ive seen on fin stabalised projectiles were tested in shotguns, and it pretty much always either breaks from the wading pushing on the fins or just tumbles anyway and would of been more accurate without fins. But this is different since its being pushed from pressure on the body instead of the fins.

Im no rocket scientest but im not sure the fins would actually be guiding air at 1kfps or so, i think the air would be making a cone around it and stability would come from the front half weighing more than the back half. If this were made of lead g forces on launch would be wanting to strectch the fins back or break it off since it seals in the front its basically pulling away from stationary fins. To counter that youd need a thicker center stem and fins but the more you do that the more you mess up the balance and it may tumble.

Im unsure if lead has the physical strength to work and copper would be much easier function wise. If you ask me youd be better off with just shooting a hollow base shape thats stable with no spin like many shotgun slugs and pellets. But im just a random moron so this might be useless

Lots to think about there. In 300 Blackout with a really heavy projectile you might be staying subsonic, plus there are things you can do to strengthen the alloy a bit. What about casting the projectile, then coating it with release agent and pouring half a plaster sabot around it? Let it harden then flip it and pour the other half.

Of course all of this is way too much trouble, just fun to think about. I’m not sure I know anyone who wants plaster slugs blasting down their barrels.

Casting them from zinc is another interesting option...or maybe just casting the finned tail and imbedding them in the lead nose piece.

[jdfoxinc]

Fin stabilized discarding sabot with the sabot molded plastic.

[lightman]

Thinking or acting outside of the box can have interesting results sometimes. After all, someone was the first to do the things that we consider to be standard now days! I think the military has or had some ammo with fins. Maybe in the bigger stuff, like the main gun on a tank?

[country gent]

The fletchettes used in beehive artillery rounds and shotguns by the military were fin stabilized. Sort of mini steel arrows but these were a steel forging and much harder than lead or copper. They could be fitted into a sabot to seal the bore and protect the fins. But with the sabot rifling would impart spin to projectile negating the fin stabilization. Also constant sabot release is always an issue. Here a 4 piece sabot with 4 fins or 3 piece with 3 fins may be the answer for good support and release.

Its an interesting concept and thought provoking in many ways. An angle to the fins may impart spin or like a big broadhead on an arrow steer the bullet in a detremental way. A wasp waisted bullet ( Like a bad mitten shuttlecock) may do as well.

[Elkins45]

Thinking or acting outside of the box can have interesting results sometimes. After all, someone was the first to do the things that we consider to be standard now days! I think the military has or had some ammo with fins. Maybe in the bigger stuff, like the main gun on a tank?

The M1 Abrams is a smoothbore gun. The standard antitank round is a giant metal dart fired with a discarding plastic sabot. It’s made of extremely dense metal like tungsten or depleted uranium and relies on pure kinetic energy to kill a tank.

[lightman]

The M1 Abrams is a smoothbore gun. The standard antitank round is a giant metal dart fired with a discarding plastic sabot. It’s made of extremely dense metal like tungsten or depleted uranium and relies on pure kinetic energy to kill a tank.

Thanks for posting this. I'm always interested in stuff that I have never been around.

[LongRangeAir]

And the Abrams Sabot Round is Fin Stabilized. :<)

KnifeMaker

[pashiner]

Look into the BRI sabot shotgun round marketed by winchester. A projectile like that...essentially an elongated diabolo airgun pellet of .50 caliber inside a .73 sabot is stable and accurate through both rifled and smoothbore barrels. This could be scaled down to .30 and shot without a sabot in a .300blk. No fins, but effective drag stabilization, very good ballistic coefficient, and an easy mold to make. 2 mold halves, a core pin, and nose-pour could get the job done.