T4E-HDR/HDS 23gr Slugs @1100-1400 fps, Would They Fly Accurately?

[Triglav]

Hello everyone,
I've found myself having a huge dillema on whether to buy some 19-24gr T4E .50 Cal projectiles of all kinds, including steel-tipped slugs, aside from just the basic plastic, or otherwise rubber balls; Or on the other hand not to buy them...

These projectiles would be flying really fast, at some 1100 to 1450 fps at the muzzle, by my estimation, and would develop around 35-50 ft/lbs of muzzle energy, although out of a relatively short barrel - only 3.16" long. Would these kinds of projectiles be able to hit a water bottle at 10 yards or so? I reckon the ball shaped 19gr projectiles would, due to their shape. However, I doubt that the ~24gr slugs would fly straight, because of all their weight being distributed at the front, forward of the middle area, due to the steel ball-bearing being positioned there.

I'm talking about these ones:

Spezialgeschosse Slugmakers Best TurboTwist.50 für CO2 Markie...

Durch die turbinenartigen Leitwerke im vorderen Bereich wird der TurboTwist.50 beim Abschuss in eine schnelle, längs-Rotation versetzt. Dadurch ist das Geschoss...

www.versandhaus-schneider.de

Is there a way to theoretically test the stability of these slugs at such a high speed at all?!
They're quite expensive for my budget, at a euro.15 per piece from one of my local stores... And with that said, I'm not buying until I get a somewhat reliable answer from one of you guys. I'd really like to know and 'd like to thank anyone who has ever experimented with slugs in advance - It's a pretty unknown territory when it comes down to these T4E slugs

Have a good one y'all!

 

[Motorhead]

Teetering on supersonic / deep into transonic never read anyone having controllable stability no mater the projectile type.

 

[Bernie7]

Hello everyone,
I've found myself having a huge dillema on whether to buy some 19-24gr T4E .50 Cal projectiles of all kinds, including steel-tipped slugs, aside from just the basic plastic, or otherwise rubber balls; Or on the other hand not to buy them...

These projectiles would be flying really fast, at some 1100 to 1450 fps at the muzzle, by my estimation, and would develop around 35-50 ft/lbs of muzzle energy, although out of a relatively short barrel - only 3.16" long. Would these kinds of projectiles be able to hit a water bottle at 10 yards or so? I reckon the ball shaped 19gr projectiles would, due to their shape. However, I doubt that the ~24gr slugs would fly straight, because of all their weight being distributed at the front, forward of the middle area, due to the steel ball-bearing being positioned there.

I'm talking about these ones:

Spezialgeschosse Slugmakers Best TurboTwist.50 für CO2 Markie...

Durch die turbinenartigen Leitwerke im vorderen Bereich wird der TurboTwist.50 beim Abschuss in eine schnelle, längs-Rotation versetzt. Dadurch ist das Geschoss...

www.versandhaus-schneider.de

Is there a way to theoretically test the stability of these slugs at such a high speed at all?!
They're quite expensive for my budget, at a euro.15 per piece from one of my local stores... And with that said, I'm not buying until I get a somewhat reliable answer from one of you guys. I'd really like to know and 'd like to thank anyone who has ever experimented with slugs in advance - It's a pretty unknown territory when it comes down to these T4E slugs

Have a good one y'all!

I just want to provide some context. My understanding of CO2 powered paintball pistols is they run around 4-12 fpe when using rubber “riot rounds”. The manufacturer data puts the t4e at 7.5 fpe so you’ll be well below subsonic.

Using a ballistic calculator you can extrapolate the fps/mps. I’ll edit this comment in a moment when I find the really good one I like.

Okay here’s the good one, https://www.omnicalculator.com/physics/bullet-energy you can enter energy and mass and it works out projectile weight, or enter energy and speed to get mass. Most only allow entering mass and speed and then it spits out fpe.

 

[Bernie7]

The other thing is you’re shooting at a pretty short range, that combined with the apparent rifling of the sabot/exterior of the projectile should provide some spin stabilization to it. And in this case you actually want a projectile with the mass forward with a tail fin hence the classic “diabolo” shape of a pellet as the drag created in the rear prevents the projectile from rotating along the x & y axis (in this case, z axis would run from the barrel to point of impact)

 

[Ballisticboy]

At the kind of speeds you are talking of, diabolo projectiles tend to be aerodynamically unstable. Aerodynamic stability is provided by the lateral moments created about the CG not the drag, and at speeds at and above Mach 1 the destabilizing lateral moments tend to be larger than the stabilizing moments from the flare at the back of the projectile. Drag makes very little or no contribution to the stabilizing moments. This thread explains the aerodynamic stability of pellets, https://www.airgunnation.com/threads/aerodynamic-stability-of-pellets.1276895/. The stability can be estimated, but it is quite a long process and needs specialist data.

Aerodynamic instability is not necessarily a problem, provided you have sufficient spin rate relative to the forward velocity for gyroscopic stability. With the pictured projectiles, I would have doubts that stability would be sufficient, particularly as all the mass is concentrated in the middle of the projectile, giving poor inertial properties for stability.

There are projectiles which have muzzle velocities in the speed range you are describing which fly perfectly happily, but they look nothing like the ones you are thinking of. It is all a matter of design. It all depends on what you want to do with the projectiles and how far you want to shoot them. I would only use them at very short ranges and not expect very much from them.

 

[Bernie7]

At the kind of speeds you are talking of, diabolo projectiles tend to be aerodynamically unstable. Aerodynamic stability is provided by the lateral moments created about the CG not the drag, and at speeds at and above Mach 1 the destabilizing lateral moments tend to be larger than the stabilizing moments from the flare at the back of the projectile. Drag makes very little or no contribution to the stabilizing moments. This thread explains the aerodynamic stability of pellets, https://www.airgunnation.com/threads/aerodynamic-stability-of-pellets.1276895/. The stability can be estimated, but it is quite a long process and needs specialist data.

Aerodynamic instability is not necessarily a problem, provided you have sufficient spin rate relative to the forward velocity for gyroscopic stability. With the pictured projectiles, I would have doubts that stability would be sufficient, particularly as all the mass is concentrated in the middle of the projectile, giving poor inertial properties for stability.

There are projectiles which have muzzle velocities in the speed range you are describing which fly perfectly happily, but they look nothing like the ones you are thinking of. It is all a matter of design. It all depends on what you want to do with the projectiles and how far you want to shoot them. I would only use them at very short ranges and not expect very much from them.

First off to OP, the guy who responded here @Ballisticboy truly knows his poop. My comment was a best guess and somewhat ironically based on the article he linked (having read it awhile ago) which I guess demonstrates I didn’t read it carefully enough

Although to be sure, @Ballisticboy when you say “at the speeds you are talking of” do you mean what the OPs estimate is or what I posted and believe is a much more accurate assessment based on manufacturer’s data? The device listed is powered from a 12g CO2 cartridge (~850psi) and has a 4.25” barrel. Even at the low end of his estimate @ 1100 fps, that would give ~56 fpe, which would put it on par with a GK1 fired at ~3600psi through a longer barrel and at a heavier weight.

 

[Ballisticboy]

First off to OP, the guy who responded here @Ballisticboy truly knows his poop. My comment was a best guess and somewhat ironically based on the article he linked (having read it awhile ago) which I guess demonstrates I didn’t read it carefully enough

Although to be sure, @Ballisticboy when you say “at the speeds you are talking of” do you mean what the OPs estimate is or what I posted and believe is a much more accurate assessment based on manufacturer’s data? The device listed is powered from a 12g CO2 cartridge (~850psi) and has a 4.25” barrel. Even at the low end of his estimate @ 1100 fps, that would give ~56 fpe, which would put it on par with a GK1 fired at ~3600psi through a longer barrel and at a heavier weight.

It was based on the speeds he was guessing. At any speeds, I would be dubious about those particular rounds, and as you say with such a short barrel it ain't going to be going anywhere at high speed.

 

[Bernie7]

It was based on the speeds he was guessing. At any speeds, I would be dubious about those particular rounds, and as you say with such a short barrel it ain't going to be going anywhere at high speed.

Was my interpretation of your article regarding center of gravity and center of pressure correct if it was applied to subsonic projectiles shaped like the ones that OP planned on shooting? They seem to have a metal ball in the front with a plastic housing and tail fin->

 

[Ballisticboy]

Was my interpretation of your article regarding center of gravity and center of pressure correct if it was applied to subsonic projectiles shaped like the ones that OP planned on shooting? They seem to have a metal ball in the front with a plastic housing and tail fin->

View attachment 428241

Looking at the pictures, I don't think the metal ball will make a big difference to the CG position which could be a long way back as a result, the BB is too small compared to the plastic even though it is roughly 6 times as dense. The flare shape is also not going to be very good at producing stabilizing moments about the CG and will produce a lot of drag, whereas the front of the projectile looks as if it will give lots of lateral moments which will be destabilizing. So you may be able to hit something at 10 yards, but possible not much more.

Of course, if it is totally unstable you may still be able to hit something as rapidly tumbling bullets tend to fly relatively straight, it's just that when they hit a close target they don't have a lot of energy, and they could be sideways, backwards or any other orientation. They also don't go very far.

 

[Triglav]

Teetering on supersonic / deep into transonic never read anyone having controllable stability no mater the projectile type.

I am well aware of that, but I'm talking about shooting these at 15yds max.

 

[Triglav]

I just want to provide some context. My understanding of CO2 powered paintball pistols is they run around 4-12 fpe when using rubber “riot rounds”. The manufacturer data puts the t4e at 7.5 fpe so you’ll be well below subsonic.

Using a ballistic calculator you can extrapolate the fps/mps. I’ll edit this comment in a moment when I find the really good one I like.

Okay here’s the good one, https://www.omnicalculator.com/physics/bullet-energy you can enter energy and mass and it works out projectile weight, or enter energy and speed to get mass. Most only allow entering mass and speed and then it spits out fpe.

View attachment 428029

Ok, so a heavier 23gr .50 cal slug (steel-tipped) would be flying out of the adapter at ~850+ fps, generating some 33 ft/lbs of muzzle energy. MORE than enough for me, but would the fly straight?!

I'll check out the other answers in this thread...

 

[Bernie7]

Ok, so a heavier 23gr .50 cal slug (steel-tipped) would be flying out of the adapter at ~850+ fps, generating some 33 ft/lbs of muzzle energy. MORE than enough for me, but would the fly straight?!

I'll check out the other answers in this thread...

I’m not going to say it’s impossible but can you please post the reference for that energy level?
Thank you!

 

[Triglav]

The other thing is you’re shooting at a pretty short range, that combined with the apparent rifling of the sabot/exterior of the projectile should provide some spin stabilization to it. And in this case you actually want a projectile with the mass forward with a tail fin hence the classic “diabolo” shape of a pellet as the drag created in the rear prevents the projectile from rotating along the x & y axis (in this case, z axis would run from the barrel to point of impact)

The thing is, these projectiles are essentially a foster-pellet hybrid, because of a "diabolo" styled skirt and its inherent radial rifling, all around the sides of the slug. That's why my initial thought was, that they would fly accurately out to maybe 7 yds, however I cannot assume the same for up to 15 yds or so, which is a good double of that distance... It may sound close, but when you get there to try it out, it's a mile far!

I might have some with a larger tail fin 3D printed, and I'm going to use slingshot BBs 9.5mm as a tip. The overall shape of the body would remain unchanged.

 

[Triglav]

I’m not going to say it’s impossible but can you please post the reference for that energy level?
Thank you!

What do you mean by "reference"?
A gun I'd shoot these slugs with, is that what you meant?

 

[Triglav]

At the kind of speeds you are talking of, diabolo projectiles tend to be aerodynamically unstable. Aerodynamic stability is provided by the lateral moments created about the CG not the drag, and at speeds at and above Mach 1 the destabilizing lateral moments tend to be larger than the stabilizing moments from the flare at the back of the projectile. Drag makes very little or no contribution to the stabilizing moments. This thread explains the aerodynamic stability of pellets, https://www.airgunnation.com/threads/aerodynamic-stability-of-pellets.1276895/. The stability can be estimated, but it is quite a long process and needs specialist data.

Aerodynamic instability is not necessarily a problem, provided you have sufficient spin rate relative to the forward velocity for gyroscopic stability. With the pictured projectiles, I would have doubts that stability would be sufficient, particularly as all the mass is concentrated in the middle of the projectile, giving poor inertial properties for stability.

There are projectiles which have muzzle velocities in the speed range you are describing which fly perfectly happily, but they look nothing like the ones you are thinking of. It is all a matter of design. It all depends on what you want to do with the projectiles and how far you want to shoot them. I would only use them at very short ranges and not expect very much from them.

Thanks a LOT for this, the thread you linked is the one I've been searching for a while now, but for some reason this sites' "search" function didn't find it for me, for some reason or another... Once again, thank you! Although, as you've already stated about the specialist data on the matter, this isn't exactly going to come in handy on the matter of these slugs (well, not in particular, only gennerally speaking), but will certainly serve me just right in regard to shooting slugs with my airguns (I only have break barrels), but the H&N 21 grainers will most likely work out of my Hatsan 125 and now I can finally (at least theoretically) put the matter into perspective with the use of the data from that thread.

The thing about propelling these slugs is only somewhat similar to airguns, but not entirely related (although it's still airgun/CO2 guns ammo after all) - that's why I posted the question on stability@such FPS to this site.

Other than that, I assumed that these probably wouldn't exactly be good for anything other than short range plinking, just as you've described in regard to the design of the projectiles and the inertial stability associated with it.

Thank you for this elaboration, really!

 

[Bernie7]

What do you mean by "reference"?
A gun I'd shoot these slugs with, is that what you meant?

If there was a video where someone shot these projectiles out of a CO2 power pistol and chronographed them? And yes, ideally if they specifically used the T4E..

I found a video where they fire solid steel slugs

Jump to 7:50 to see the chrono results, I believe he also has a custom built barrel extension.

Maybe @Ballisticboy can chime in but I’ve found it appears that adding mass to a projectile increases energy given all other factors remain constant. I’m sure there’s a break even point though where it starts to work in reverse where the pressure is insufficient to even get the projectile to leave the barrel or due to additional friction from more surface area touching the bore so even if the energy was technically equivalent or greater it wouldn’t actually serve a practical purpose. Once again I’m theorizing based off personal experience and limited knowledge, hopefully an expert can provide an answer.

 

[Savagefox]

NOTHING out of those pistols fly accurately, I 3D print all kinds of projectiles and shapes, one of them even make a friking spyral in front of me and go to the sky.

The only things that kinda worked are plain round ammo or cilindrical blocks with no shape at all, and neither of those are accurate, but at least you will hit the board.

 

[Triglav]

First off to OP, the guy who responded here @Ballisticboy truly knows his poop. My comment was a best guess and somewhat ironically based on the article he linked (having read it awhile ago) which I guess demonstrates I didn’t read it carefully enough

Although to be sure, @Ballisticboy when you say “at the speeds you are talking of” do you mean what the OPs estimate is or what I posted and believe is a much more accurate assessment based on manufacturer’s data? The device listed is powered from a 12g CO2 cartridge (~850psi) and has a 4.25” barrel. Even at the low end of his estimate @ 1100 fps, that would give ~56 fpe, which would put it on par with a GK1 fired at ~3600psi through a longer barrel and at a heavier weight.

If there was a video where someone shot these projectiles out of a CO2 power pistol and chronographed them? And yes, ideally if they specifically used the T4E..

I found a video where they fire solid steel slugs

Jump to 7:50 to see the chrono results, I believe he also has a custom built barrel extension.

Maybe @Ballisticboy can chime in but I’ve found it appears that adding mass to a projectile increases energy given all other factors remain constant. I’m sure there’s a break even point though where it starts to work in reverse where the pressure is insufficient to even get the projectile to leave the barrel or due to additional friction from more surface area touching the bore so even if the energy was technically equivalent or greater it wouldn’t actually serve a practical purpose. Once again I’m theorizing based off personal experience and limited knowledge, hopefully an expert can provide an answer.

You're exactly right about this, your personal experience didn't fail you! Once either a barrel gets too long, or the projectile too heavy, the muzzle velocity and with that muzzle energy/power starts to go down, due to a variety of factors - i.e. backpresure, gas expansion threshold, friction of the projectile... et cetera. I know this for certain, but with CO2 there's something else at play, and that's the fact that the greater the caliber is, the more effect the gas will have on the expansion of pressure - that's also in regard to the material of which the barrel is made; Copper and brass work best for adding to backpressure.

By the way, the extended barrel mod on that HDR in called the XTender.