Bullet expansion vs. penetration

[Hanuman]

So I took the time to re-read all the weapon descriptions. Noticed some interesting things; the 7mm is described as light-weight, even though at 4.5 weight units it is heavier than most rifles besides the .338 and .470 but what struck me was that the 6.5 mm is described as having "above average penetration", and I have found for a class 4-8 rifle it has little punch.

I started looking at expansion values vs. penetration values for the different caliber rifles and wondered the following; When a round hits a target, it expands on impact and while penetrating the animal. This expansion causes impact damage (kinetic damage), but when a round expands, that should reduce penetration. So I wondered if two rounds that have the same penetration value, but different expansion values, does that alter "true" penetration?

I took the most common calibers and looked at expansion vs. penetration and expansion/penetration to get a sense of how much the bullet expands as it penetrates.

Caliber Expansion Penetration Expansion/Penetration
.243 4 30 0.13
.270 5 35 0.14
.30-06 11 40 0.28
.300 14 42 0.33
.338 16 45 0.36
6.5mm 4 40 0.1
7mm 12 40 0.3

This seems to show that the 6.5mm round expands far less, as it travels through the animal and encounters resistance. I think it's an interesting outlier. I wonder if this is why its labeled as having high penetration eventhough its value of 40 isn't that over the top.

Anyhoe, I still struggle accepting the 6.5mm is a good choice.

What you guys think? Am I looking at this right?

Cheers!

[Hanuman]

Sorry for the messy formatting. Its four columns showing caliber, expansion, penetration and expansion divided by penetration to give expansion as the bullet penetrates.

If they made the 6.5mm class 3-6 I think it would be perfect?

[yogisgoat]

It does have high penetration for its' size. The slug is .264 in diameter but has the same penetration as the 7mm which is .284 diameter.

Personally, I think the 6.5 is overrated. For a mid-range rifle I find either the Eckers or the Garrand to be best. Hits almost as hard as the 7mm with the chance for a quick follow-up shot. There's a reason why the .308/7.62mm caliber is the most popular big game slug in the world. Even the lowly 30/30 is actually a .308 cal and is actually quite capable for close range work.

[Hanuman]

Thanks Yogi and Dark for the input. I have been using the M1 a lot lately (over the Eckers). I wonder if the supposed high penetration of the 6.5mm round is due to the shape of the tip. Thanks for turning the 6.5mm metric into imperial, I didn't know the 6.5mm is equivalent to .264 (didn't do the math).
I sort of assumed the 6.5mm was much larger caliber than the .243. I know very little about real rifles. It's weird how the ingame 7.62mm (correct me if I am wrong but that is the Solokhin right?) states it has "deadly penetration" but only offers soft-point rounds.

[Katatonik]

my simple understanding is that penetration is able to penetrate the animal thick skin so you can hit the organ, but leave a little hole that the bleeding rate is not great.

As for the bullet expansion, it cannot really penetrate, but it "explode upon impact" that leave the animal with a gaping wound that will make them bleeding profusely.

[gabcik&kubis]

Originally posted by OddOneOut:

my simple understanding is that penetration is able to penetrate the animal thick skin so you can hit the organ, but leave a little hole that the bleeding rate is not great.

As for the bullet expansion, it cannot really penetrate, but it "explode upon impact" that leave the animal with a gaping wound that will make them bleeding profusely.

So some explanation:
- entry wound is usually small regardless the bullet. It doesn't have time to expand. Some bullets have rim that works like cutting edge to make regular hole that do not seal itself and increases external bleeding
This is why there was/is requirement for the bullet to cross penetrate animal as exit wound tends to be larger thus it is easier to track animal if necessary - besides generally increased damage
- penetration rounds expands a little, slowly or do not expand at all - depends on requirements. It is mandatory that they are strongly built and do not disintegrate, loose parts even when hitting bones, otherwise they penetrate less.
But even modern expanding bullets are judged by their ability to retain their original mass - for the same reason
- expanding bullets do not explode. They turn into mushroom. In this way they transfer their energy into body of the animal, they increase permanent cavity (channel left behind them) as well as temporary cavity (like if you throw a stone into a water, it makes channel that collapses). In this way they cause more local damage, increase bleeding - internally as well as externally and probably also can cause penumothorax when lungs are hit.
Very fast bullets are also said to cause shock effect that can be deadly on itself or at least incapacitating

Unfortunately, there is general agreement that all bullets in the game are under-performing in terms of penetration and damage power in case of the proper shot placement (direct heart, brain or spine cord hits excluded for obvious reason).

[Alpaca Rotorvator]

Originally posted by Dream Master:

When a round hits a target, it expands on impact and while penetrating the animal. This expansion causes impact damage (kinetic damage), but when a round expands, that should reduce penetration. So I wondered if two rounds that have the same penetration value, but different expansion values, does that alter "true" penetration?

This seems to show that the 6.5mm round expands far less, as it travels through the animal and encounters resistance. I think it's an interesting outlier. I wonder if this is why its labeled as having high penetration eventhough its value of 40 isn't that over the top.

Originally posted by gabcik&kubis:

Originally posted by OddOneOut:

my simple understanding is that penetration is able to penetrate the animal thick skin so you can hit the organ, but leave a little hole that the bleeding rate is not great.

As for the bullet expansion, it cannot really penetrate, but it "explode upon impact" that leave the animal with a gaping wound that will make them bleeding profusely.

So some explanation:
- entry wound is usually small regardless the bullet. It doesn't have time to expand. Some bullets have rim that works like cutting edge to make regular hole that do not seal itself and increases external bleeding
This is why there was/is requirement for the bullet to cross penetrate animal as exit wound tends to be larger thus it is easier to track animal if necessary - besides generally increased damage
- penetration rounds expands a little, slowly or do not expand at all - depends on requirements. It is mandatory that they are strongly built and do not disintegrate, loose parts even when hitting bones, otherwise they penetrate less.
But even modern expanding bullets are judged by their ability to retain their original mass - for the same reason
- expanding bullets do not explode. They turn into mushroom. In this way they transfer their energy into body of the animal, they increase permanent cavity (channel left behind them) as well as temporary cavity (like if you throw a stone into a water, it makes channel that collapses). In this way they cause more local damage, increase bleeding - internally as well as externally and probably also can cause penumothorax when lungs are hit.
Very fast bullets are also said to cause shock effect that can be deadly on itself or at least incapacitating

Unfortunately, there is general agreement that all bullets in the game are under-performing in terms of penetration and damage power in case of the proper shot placement (direct heart, brain or spine cord hits excluded for obvious reason).

Do we even know if the game simulates terminal ballistics to that extent? From observation alone it doesn't seem like it simulates any kind of expansion or wound cavities at all. Bullets just fly straight through the animal, damaging organs along the way, until they lose all energy.

Since it doesn't seem like the game simulates different types of tissue(eg. fur, skin, bone, muscle) either(but it might have different "armor" values to different animal parts), I'd suspect the way bullet stats actually work in the game is along the lines of:

• Penetration and expansion are independent(ie. interaction effects such as the bullet losing penetration ability as it expands are already baked into the numbers and not simulated at all)
  
• Penetration dictates how far inside the animal a bullet can go. The actual final result seems to be affected by the animal you're shooting and shot distance as well.
  
• Expansion simply increases the damage you deliver to the animal.
  
• This is a bit of a jump of faith, but I'd posit bleed rate is more related to the type of ammunition than anything else

But ultimately this is all conjecture.

Originally posted by Dream Master:

I took the most common calibers and looked at expansion vs. penetration and expansion/penetration to get a sense of how much the bullet expands as it penetrates.

Caliber Expansion Penetration Expansion/Penetration
.243 4 30 0.13
.270 5 35 0.14
.30-06 11 40 0.28
.300 14 42 0.33
.338 16 45 0.36
6.5mm 4 40 0.1
7mm 12 40 0.3

This seems to show that the 6.5mm round expands far less, as it travels through the animal and encounters resistance. I think it's an interesting outlier. I wonder if this is why its labeled as having high penetration eventhough its value of 40 isn't that over the top.

Anyhoe, I still struggle accepting the 6.5mm is a good choice.

What you guys think? Am I looking at this right?

Cheers!

Speaking as someone very biased because I really want the 6.5 not to suck, I'd guess the devs intended for its low expansion to be compensated by relatively high penetration, decent accuracy and relatively flat trajectory. Like something you could use to take on the whole range of class 4-6 animals on Cuatro Colinas(the map it came out with IIRC) from mid to long range. A .223 on steroids of sorts.
Does it work well for that purpose? Kinda. Are there better, more versatile rifles for the ranges one usually engage animals with(50~130m for me)? Absolutely. So yeah, kind of a solution looking for a problem situation in most cases

[El Poto]

Yeah, the performance in this game for all the bullets is quite underwhelming. I know they need this to be "gamey", however, Classic still beats COTW in this department.

Also, what's really the point of soft point bullets? It seems they're just a filler while you're leveling up.

[Hidden Gunman]

First off, don't think of the game's ballistic dynamic in real life terms, the game is not a sim and the terminal ballistics are not modeled in those terms - they are driven by the game's unlock mechanic and 'thematic realism'.

Second, in reality there is a lot of misconception and misinformation in the world of firearms terminal ballistics, talk of 'hitting power' and 'shock effects' and the like. The reality is though that only two things count when an animal (or person) is struck by a projectile - the size of the hole, and what was damaged in the making of that hole. The size of the hole (referred to as the permanent cavity) determines bleed rate, while the damage to structure (such as organs, blood vessels, etc) determines the physiological effects such as loss of function and organ failure. Modelling of those effects in the real world is actually debatable, and in consideration of the extensive and broad use of firearms throughout history is surprisingly lacking in definitive knowledge, which is largely based on anecdotal sourcing rather than empiric experimentation.

In game terms though, I doubt we know enough about the equation the devs are using to get anything but a rough idea on how their model works. That said, the issue will always revolve around the unlock mechanic - expanding projectiles and penetrating projectiles are not alternatives to each other, the expanding projectiles are the base model, and the penetrators are the upgrade. The firearms themselves simply provide a spread of choice across varying classes of game animal.

[Hanuman]

Thank you everyone for the excellent posts. Interesting stuff.

[El Poto]

"expanding projectiles and penetrating projectiles are not alternatives to each other, the expanding projectiles are the base model, and the penetrators are the upgrade"

I don't agree. The time it takes to unlock the "upgrade" makes expanding ammo simply irrelevant. Even in my first playthrough I only used expanding bullets for the .243, because that's all you have day one. But after that I never ever wasted my time using the expansion versions, except for a little testing that told me they weren't worth.

As things stand, the devs should get rid of the expanding ammo, or give them a different purpose. Perhaps buffing them in a way that a well placed shot would give 100% quick kill, varying the effective range, or whatever to make them more interesting.

[Humpenstilzchen]

I generally agree that all sorts of ammo need a buff in this game, especially the soft tip rounds.
The only exception seems to be the solokin, the penetration of it isn´t not that bad comparted to other soft tip rounds of the game. Maybe they made it a bit stronger because there is no hardcast ammo for this rifle idk.
https://steamcommunity.com/sharedfiles/filedetails/?id=2271752051

[El Poto]

Well, the Solokin only has soft tips. However, from what I remember, is a very special type of ammo, which is probably why that gun is so effective.

[Hidden Gunman]

Originally posted by El Poto:

"expanding projectiles and penetrating projectiles are not alternatives to each other, the expanding projectiles are the base model, and the penetrators are the upgrade"

I don't agree. The time it takes to unlock the "upgrade" makes expanding ammo simply irrelevant. Even in my first playthrough I only used expanding bullets for the .243, because that's all you have day one. But after that I never ever wasted my time using the expansion versions, except for a little testing that told me they weren't worth.

As things stand, the devs should get rid of the expanding ammo, or give them a different purpose. Perhaps buffing them in a way that a well placed shot would give 100% quick kill, varying the effective range, or whatever to make them more interesting.

That's my point, but I should have said "...of each other...", rather than "...to...". If the wound modelling was more realistic, with structure damage rather than simply kill/wound, then the two ammunition types would be useful as alternatives.

[keithcollett]

with this system they are using now, I use the 7,62, 8 x 16 scoop, 2 shoots, wait for it to die, most shoot are around 200 to 250yds, I just go for centre of target, bang bang, no real arming, thats any animal, rabbit to a buffolow, but for 100yd kills, the good old Sharps Rifle, best all round bullit, you do have to arm it as it takes time to re-load, 1 shoot one kill,