Hey guys am new here, greetings from Austria. I have recently looked at various shapes of armor piercing cores. The nose/tip shapes of the cores are partly very different. My question is what is the most effective shape to pierce through steel armor?

Ogive (secant/tangent) shape, concial nose shape or a hybrid shape?

To be clear, i'm talking about the tungsten penetrator core. Not the whole bullet shape.

Thank's for any input.

Welcome to the forum. 

Probably depends on composition of the core, the composition of the armor you're trying to penetrate, and the angle of impact. Stancrist and Schuersi will know for sure.

Farmplinker said:

Probably depends on composition of the core, the composition of the armor you're trying to penetrate, and the angle of impact.

It does.

Generally speaking you want a blunt penetrator nose. These offer the best compromise of properties. Most important they are less suceptible to impact angle and they will not break off.

Now here comes the but: the ability to produce a penetrator is at least as important as its ability to penetrate. Usually not the optimal shape for penetration but for production is picked. At best its a compromise between the two. The materials used as well as the exact dimensions also play a role.

Armor penetration is a very complex problem. Slight changes in parameters result in different optimums.

Ideal for deep penetration trough steel are long rod penetrators. These are basically exactly what the name says. A rod. A long cylindrical shape. Often the ends of the Penetrator don't have any special shape themself. The penetration is achieved by brute force and creating fluiddynamic displacement. Which is the most efficient way to penetrate trough steel (or metals in general) Small arms are usually not powerfull enough for this though.

Long story short: to get a more precise answer to your question, we need a more precise question.

Thanks for the answer.
So more precise questions. Lets say we want to design a sabot and a tungsten core, caliber .510 . The goal is to penetrate one inch AR500 at 100 yards. To get the desired result, a high muzzle velocity will be necessary.

The first question in this case would be: tungsten heavy alloy or tungsten carbide (WC-Co alloy)? Which would be more effective. I mean there is a reason that tungsten carbide works better in smaller calibers and tungsten heavy alloy in calibers 20mm and larger. At higher muzzle velocities, tungsten carbide tends to shatter on impact.

The second question concerns the overall shape of the core and the shape of the nose. What would be the optimal nose shape to punch through one inch AR500?
(At an impact angle of 90°.)

Of course, weight and muzzle velocity are the next factors, but let's go from here. 

APFSDST said:

The goal is to penetrate one inch AR500 at 100 yards. To get the desired result, a high muzzle velocity will be necessary.

Not really.

You can perforate a 25 mm HHA plate at 100 yard with a regular .50'', full-calibre, steel core bullet like the RUAG HC.

The 1980-era Manhurin 12.7 mm PI F1 (API) was a full-calibre bullet with a tungsten carbide core, and was able to defeat a 25 mm RHA plate at en impact velocity of only ~640 m/s. Using HHA will probably do not change the required impact velocity by a large margin.

The current .50'' SLAP (M903) could defeat something like 50 mm of armor at 100 m, using a WC core and a sabot is probably overkill if your goal is just to defeat 25 mm of HHA at 100 m.

Fully agree with EmericD one inch/24,7 mm at 100 m for a .50/12,7 mm weapon is not really a challenge.

Allmost all inter war era AT-rifles manage that. Sometimes with smaller calibers.

The thing is you have to take manufacturing of the ammo into account. With your specifications I could immediately suggest a fin stabilised long rod penetrator at an MV in excess of 1200 m/s and get the desired or better penetration at 1000 m. But the ammo would be a nightmare to produce and extremly expensive. Wich is why we do not see such weapons.

Generally speaking you want to avoid sabots in small arms. They are doable and work but they are unnecessary complicated and expensive. There is a point of dimishing returns. As a rule of thumb the smallest caliber to use fin stabilised long rods is 25 mm. Below that APDS is used. With .50 being the smallest caliber where sabots in general make sense. The full caliber Mk211 with AP core is conciderable more common for .50 cal than APDS/SLAP.

APFSDST said:

The first question in this case would be: tungsten heavy alloy or tungsten carbide (WC-Co alloy)?

This again is a question of manufacture. Tungsten heavy alloy is preferable but it depends on avialblility and being able to actually make penetrators from the material. This is why usually, especially for small calibers that are used a lot, the cheaper WC is used. Its cheaper to make and to create penetrators form it.

APFSDST said:

The second question concerns the overall shape of the core and the shape of the nose. What would be the optimal nose shape to punch through one inch AR500?

Such a penetrator shap is a good compromise. Its pretty blunt. So impact angle is not that critical. The tip will not break off easily. Because of the rather simple shape its easy to manufacture in large quantities. The above round also delivers the desired performance plus very good behind armor effect.

APFSDST said:

tungsten carbide (WC-Co alloy)

BTW: WC is not an alloy. Its a ceramic (WC) in a metal (Co) matrix.

Usually the approach to design a weapon is to define a target first. This gives a required performance. What it 1" of AR500 going to be? Just penetrating also is not enough. Depending how penetration is defined a round designed to deliver exactly just that might not have any noteworthy behing armor effect at all.

Too many people don't even know about much less consider behind armor effect even though it's absolutely critical.

Most of the pictures and videos I have seen about armor piercing ammunition, some on YouTube, show that most rounds fail to penetrate 1" ar500 at 100 yard. Even the 50BMG AP rounds.

Yes, the SLAP M903 did the trick, it just went through the 1" AR500. However, the regular 50 cal AP rounds, they did not go through. I don't disagree with your post.

Probably most people on YouTube don't have access to new AP ammo either way, the law is the limiting factor. Most of what you see there is AP ammo from old stocks, sometimes even from WWII.

Fun fact, one guy even tried it with 20x110mm AP, but it was a failure. No hole through the 1" AR500 plate. If anyone is interested? I can link the video here.

schnuersi said:

The thing is you have to take manufacturing of the ammo into account. With your specifications I could immediately suggest a fin stabilised long rod penetrator at an MV in excess of 1200 m/s and get the desired or better penetration at 1000 m. But the ammo would be a nightmare to produce and extremly expensive. Wich is why we do not see such weapons.

Long rod penetrator and 1200m/s+ sounds great. The problem in reality is the law but even in this theoretical scenario.
The second problem, there will never be a 50bmg long rod penetrator. Even if we are not talking about 50bmg but instead just .510 caliber. Just pretty hard to make that, the size ist too small for a .510 APFSDS.

By the way, why is everyone sticking with WHA ( tungsten heavy alloy) for APFSDS ammo? The 120mm SHARD from Nexter. It is not a tungsten heavy alloy. According to various internet sites, it's a new D10 tungsten carbide alloy in collaboration with Plansee.

Let's stick with .510 AP bullets for a minute. If 1 "AR500 is not a challenge. How about 2" AR500 at 100 yard. Not even the M903 SLAP can make it through. If you want you can watch it on youtube. 2" AR500 has stopped every 50 AP round so far, even at short range. The question is how would you design a .510 bullet if your goal was to punch through 2"? If that is even possible. The penetration power for the mk149 20x102mm is specified as 1.2 inch RHA. 1.2" RHA is a far away from 2" AR500...

All the following pictures. None of this was able to penetrate 2" AR500. Not even the mk149.