Hollowpoint Skiving/Serration on Slugs

[Airgun-hobbyist]

That's interesting, but I have doubts about it creating any lift. I'm more interested in making a slug that stops near instantly upon impact with a soft target.

I guess I should have been more clear there... If cut correctly, it would likely loose less drop at long distances compared to a similar weighted and profiled bullet. Wing lift profile has long been established in science, and with CNC programming and cutting ability nowadays it be applied here.

 

[Long_Shot]

I don't think beating on a precision projectile with a hammer and tool is the way to go.
But, what do I know.
Here's a photo of the results of a slug that is exactly the same weather for a target or fragmenting/hunting.
Clearly long range accuracy and consistency aren't a problem.

 

[Ballisticboy]

I guess I should have been more clear there... If cut correctly, it would likely loose less drop at long distances compared to a similar weighted and profiled bullet. Wing lift profile has long been established in science, and with CNC programming and cutting ability nowadays it be applied here.

When your projectile is spinning at quite a few thousand RPM the lift is not going to be pointing in any direction long enough to make any difference.

 

[Airgun-hobbyist]

When your projectile is spinning at quite a few thousand RPM the lift is not going to be pointing in any direction long enough to make any difference.

I'm not thinking so much in the terms of "true lift" so much, but an air foil that prevents less gravitational drop. More in line with the same principle/theory of a helical fletching catching wind, coupled with a plane prop/wing air foil.

 

[JungleShooter]

Thanks for the idea with a Torx screwdriver.

In a moment (or a month) of insanity — I was seriously considering getting a Corbin set and making those fragmenting extreme hollow points.

Then (financial) reality set it, and bought a set of 10 philipps screwdriver heads (at half a percent of the Corbin price).
I just haven't done the testing....


I just need extreme explosive expansion in .22 (33FPE) and .25 (50FPE) — with 3 moa precision precision — at ranges out to 40m (30m would do, 50m would be great).

Matthias

 

[Ballisticboy]

I'm not thinking so much in the terms of "true lift" so much, but an air foil that prevents less gravitational drop. More in line with the same principle/theory of a helical fletching catching wind, coupled with a plane prop/wing air foil.

To give less gravitational drop, you need a force acting in the vertical direction for a significant amount of time, or a significant reduction in flight time. On a spinning body you only have the body itself which can produce significant side or vertical forces, everything else is spinning around with it. A grossly gyroscopically overstable body can give lift and reduce the gravity drop, but in doing so produces other undesirable forces and moments, mainly from horrendous cross wind effects. Anything giving lift forces on the front risks increasing projectile yaw angles which will nutate and precess round, risking large spirals. It was tried when canards were put on the front of shells to try to guide them in flight, it doesn't work as the canards sit on the centre of pressure. Yes the shell body was at a large yaw angle producing body lift in the direction you want, but to hold it at an angle, because they were on the nose, the canards had to produce an equal force in the opposite direction giving zero net lift. What you did get was horrendous Magnus forces in random directions, giving unpredictable changes in trajectory.

As for reducing flight time, it has been tried by putting propellors on the back of spinning shells, but the propeller itself produces drag and also massively increases spin damping which will make the projectile become unstable and give very little reduction in forward velocity loss. Helical vanes, fletching etc. will be less efficient than propellors and thus worse.

 

[Airgun-hobbyist]

To give less gravitational drop, you need a force acting in the vertical direction for a significant amount of time, or a significant reduction in flight time. On a spinning body you only have the body itself which can produce significant side or vertical forces, everything else is spinning around with it. A grossly gyroscopically overstable body can give lift and reduce the gravity drop, but in doing so produces other undesirable forces and moments, mainly from horrendous cross wind effects. Anything giving lift forces on the front risks increasing projectile yaw angles which will nutate and precess round, risking large spirals. It was tried when canards were put on the front of shells to try to guide them in flight, it doesn't work as the canards sit on the centre of pressure. Yes the shell body was at a large yaw angle producing body lift in the direction you want, but to hold it at an angle, because they were on the nose, the canards had to produce an equal force in the opposite direction giving zero net lift. What you did get was horrendous Magnus forces in random directions, giving unpredictable changes in trajectory.

As for reducing flight time, it has been tried by putting propellors on the back of spinning shells, but the propeller itself produces drag and also massively increases spin damping which will make the projectile become unstable and give very little reduction in forward velocity loss. Helical vanes, fletching etc. will be less efficient than propellors and thus worse.

With regards to ideas and patents etc, they say something to the effects of, ''if you have thought of it, so has someone else'. Thanks for the insight. You are always an education.

 

[Engg.Ken]

If I am to make a design that works under 50 meters and has either torx or phillips head hollow point in the slug will it be ok? because by doing so I cant guarantee 100 meter accuracy but an expanding slug under 50 meters with great accuracy.

 

[Stretchearstrong]

Thanks for the idea with a Torx screwdriver.

In a moment (or a month) of insanity — I was seriously considering getting a Corbin set and making those fragmenting extreme hollow points.

Then (financial) reality set it, and bought a set of 10 philipps screwdriver heads (at half a percent of the Corbin price).
I just haven't done the testing....


I just need extreme explosive expansion in .22 (33FPE) and .25 (50FPE) — with 3 moa precision precision — at ranges out to 40m (30m would do, 50m would be great).

Matthias

Make sure to protect the base of the slug. I noticed some deformation that caused some difficulty in chambering afterwards. Which will certainly lead to a decrease in accuracy.

 

[Stretchearstrong]

If I am to make a design that works under 50 meters and has either torx or phillips head hollow point in the slug will it be ok? because by doing so I cant guarantee 100 meter accuracy but an expanding slug under 50 meters with great accuracy.

Not sure what you mean by "will it be okay"
It's not going to damage your rifle, but depending on how you modify the slug it might deform it slightly which WILL effect accuracy.

 

[Stretchearstrong]

Thanks for the idea with a Torx screwdriver.

In a moment (or a month) of insanity — I was seriously considering getting a Corbin set and making those fragmenting extreme hollow points.

Then (financial) reality set it, and bought a set of 10 philipps screwdriver heads (at half a percent of the Corbin price).
I just haven't done the testing....


I just need extreme explosive expansion in .22 (33FPE) and .25 (50FPE) — with 3 moa precision precision — at ranges out to 40m (30m would do, 50m would be great).

Matthias

I contacted Corbin and the cost for the dies alone comes out to about 800 USD also cost prohibitive for me at this time.
I own a hydraulic press and I'm sure I could get it to hold the dies with some tinkering, but I'm busy looking to buy a home and my wife would kill me with my custom expanding slugs if I bought the dies right now haha

 

[Stretchearstrong]

I don't think beating on a precision projectile with a hammer and tool is the way to go.
But, what do I know.
Here's a photo of the results of a slug that is exactly the same weather for a target or fragmenting/hunting.
Clearly long range accuracy and consistency aren't a

I don't think beating on a precision projectile with a hammer and tool is the way to go.
But, what do I know.
Here's a photo of the results of a slug that is exactly the same weather for a target or fragmenting/hunting.
Clearly long range accuracy and consistency aren't a problem.View attachment 483366

That's obviously the issue with this, the only way you're going to ensure consistency and accuracy is with custom dies. Also why I contacted Corbin at the same time as my hillbilly experiment.

Shooting paper and cans filled with water is hardly a scientific exploration into wether or not the slugs are doing what we want them to do. Water is generally the way people take photos of hollowpoints to showcase MAXIMUM expansion, because it stops the projectile almost instantaneously, which can not be said for live game.

They might fragment, but do they STOP inside a pigeon/squirrel sized target? Twoard the start of this thread someone posted a link to someone who actually had custom dies made and tested them in ballistic gel only 2" thick, and they were either stopping or not penetrating paper less than 12" behind the gel.

 

[Franklink]

Been following along...
I'm going to try the Phillips head trick on some .20/18.9gr NSAs.

Will test 100 yard accuracy on paper and if they shoot as well with a Phillips tip as they do without, will then employ them on some prairie dogs later this week.

I'll report my findings.

 

[Stretchearstrong]

Been following along...
I'm going to try the Phillips head trick on some .20/18.9gr NSAs.

Will test 100 yard accuracy on paper and if they shoot as well with a Phillips tip as they do without, will then employ them on some prairie dogs later this week.

I'll report my findings.

Be sure to protect the base in some way! I'm thinking urethane or leather might prevent the slug base from deforming.

 

[Franklink]

Be sure to protect the base in some way! I'm thinking urethane or leather might prevent the slug base from deforming.

Thinking maybe bicycle inner tube....

 

[Stretchearstrong]

Thinking maybe bicycle inner tube....

Would be best if we had a die to do so, but at that point we should just invest in the whole corbin set! Wish there was a way to crowd fund/ group-buy them to knock down the price per set.

 

[Long_Shot]

They might fragment, but do they STOP inside a pigeon/squirrel sized target? Twoard the start of this thread someone posted a link to someone who actually had custom dies made and tested them in ballistic gel only 2" thick, and they were either stopping or not penetrating paper less than 12" behind the gel.

That someone is me. I wrote that article.
You asked if someone had "firsthand experience trying something like this?" Well I thought I did. Thanks for schooling me about expansion.
By the way a 12 oz. can of water (Hillbilly test) is about as close to a pigeon or squirrel as it gets. Very close to cadavers I've shot lots of.
Catching it without further expansion is reliable. Just need lots of plastic bags to catch them after the pass-threw.
Have fun with it...... at least your trying.

 

[lbc_PSI]

Thinking maybe bicycle inner tube....

That would work for flat based slugs. If you’re dealing with a concave base maybe you could find a hard rubber or nylon ball bearing that would match the base curvature.

 

[Stretchearstrong]

That someone is me. I wrote that article.
You asked if someone had "firsthand experience trying something like this?" Well I thought I did. Thanks for schooling me about expansion.
By the way a 12 oz. can of water (Hillbilly test) is about as close to a pigeon or squirrel as it gets. Very close to cadavers I've shot lots of.
Catching it without further expansion is reliable. Just need lots of plastic bags to catch them after the pass-threw.
Have fun with it...... at least your trying.

Hey, my mistake, I'm misread your comment.
I thought you were saying that an unmodified slug was giving you those results you posted with the can and were essentially downplaying the effectiveness of a slug with skiving.
I'm the hillbilly here, wasn't saying your testing methods were. Just that I saw the ballistic gel test and was impressed with how thorough that experiment was.

So you're Tom Gavin?

Can you share some photos of the die set, or some info on what exactly you ordered from Corbin?

I'm really interested in buying a die set and my beating on the slugs is just my way to pass the time until I'm able to afford a set of Corbin dies.

 

[Stretchearstrong]

That would work for flat based slugs. If you’re dealing with a concave base maybe you could find a hard rubber or nylon ball bearing that would match the base curvature.

We just need to group buy some Corbin dies!