Next Gen Terminal Ballistics Discussion

[Stinky Coyote]

I didn’t want to hijack the .223 thread any further with where I’d like to go with the key minds on modern terminal ballistics here at Rokslide.

Pretty sure we can all agree on a couple things to kick this party off.

• The in-flight ballistics we’ve got down pat, all the right numbers, measures and thorough understanding of it all. We’re able to maximize the peak potential of our rifles and gear now to levels never even talked about 15 years ago for most.
• The terminal ballistics we don’t have quite to the same level. This is the topic we still argue the most about as a whole, still have too many gaps, lack of potential measures, and it’s a subjective mess for most of the discussions…IE; 67 pages on the .223 thread.

So hoping we can narrow the gap between the two further with this thread. It feels like many of us can see/understand/feel and explain reasonably well a different level of understanding but it’s still a muddy experience in most discussions. Lots at play from trying to break down old, institutionalized 20th century info like ‘just throw a 180 from a 30 and you’re fine’ to the 21st century understandings we are gaining now. I feel like we’re on the cusp of a bit of an evolutionary curve here on the terminal side of things.

I’ve had some thoughts around this for awhile and started to put things on paper early in 2020. Trying to find ways to level this playing field, are there measures we are missing and could be working on to help explain things more objectively? I’ll give an example of where I’ve started to go here…

SDRR (sectional density reduction rate) is a term I came up with as a possible new measure to help explain/compare bullets to one another. In conjuction I came up with ERR (energy reduction rate) to go with that as another possible measure we could work with to help explain better the internal work. I’ll give an example using Form’s 77 gr tmk recovered from the elk and can give one of mine as well. Now I’m not trying to sell this as the way to go, I’m still trying to let my head wrap around ideas here as we go and this looks like a great forum of minds that could add to this.

So Forms 77 tmk example, initial data points to work with. Starting SD .219, Impact Velocity 1900 fps, impact energy 617 ft/lbs, distance traveled 17”, ending bullet weight 30 grains, ending SD (lets use .5” diam x 30 grains) so final SD .017. With a 2.?x expansion ratio added to the mix to show expected expansion ratios. 1.5x up to 3x sort of thing.

So in my mind there’s measurable information there we aren’t talking about yet. There are delta’s between the start of that 17” of travel and finish…those numbers aren’t currently being discussed at this point, let alone applied. There’s no current system of factory standards to measure these things so we are going to be using inconsistent mediums of ‘game’ at this point to help illustrate future potentials.

Forms recovered example shows a delta of .202 SD split up over 17” or .01188 SD per Inch, or one might be able to then convert that to an easier number to compare such as percentage of reduction per inch? In this case maybe it’s 0.1188/.202 for 5.9% SDRR (per inch) and then to help explain some of the terms like temp/permanent stretch cavities apply also the energy side of it in the same way, we started with 617 ft/lbs and dumped it all over 17” for 36.3 ft/lbs per inch or an equal 5.9% ERR.

So my vision for how to develop this further is to of course find a medium that would allow us to compare bullets equally in (gel? Not sure) but if one could do this with so much of the subjective experience we already have on known bullets from old and new…it may prove possible to compare and better predict terminal performance going forward.

Currently SD is our only indicator, and to some extent BC to help define aero/shape which forsure plays apart and I’ve largely ignored to this point so I admit if this carries on there will be more factors to include in the equation as BC is an aero measurement we use ‘in-flight’ but surely matters for the terminal swim also. I just want to start talking about how to get better measures or data points to discuss post impact. Currently we have to combine SD, with construction type(some ‘shape) to ‘imagine’ how things will play out.

I’ll leave the forum open at this point for further comments or ideas, hopefully now is the time to push this part of the equations a little further? We are definitely doing it afield and figuring lots out as we go, I’m in there hammering with a Grendel 16” and 123gr eld-m’s and it’s doing everything I can see/feel in my mind…and the .223 thread seems to be a perfect example of possibly the lower limits etc.

For a long time I thought ft/lbs was a useless measure, and maybe that will still prove true?, but after working some of this out in my mind I feel like maybe there is a way to incorporate ‘energy’ into the equations to help explain that internal work. My main formula is still primarily ‘for game intended’ matching SD, with construction, and impact velocity…get that right and there’s magic. There is a magic formula but we don’t have the best data or measures to explain that yet. Maybe better measures are thought of during this discussion?

 

[Stinky Coyote]

I have a 123gr 6.5 eld-m example I could add as a first comparison to Forms 77gr .223 example.

mine was 2100 fps impact, Start SD .252, impact velocity 2100 fps, distance traveled 18", ending weight 99.8gr, ending SD .057 (using same .5" diameter and 99.8 gr for calc.) and 1200 ft/lbs impact. So the delta's as follows, retained SD 0.195 or 0.0108 lost per inch or 5.5% SDRR and energy transferred at 66.7 ft/lbs per inch or say 5.5% ERR. Some of these calcs. do show different rates between SDRR and ERR btw but it all depends on how much expansion you get and if it's similar it seems to show similar but if you have a 1.5x expansion vs a 3x expansion then there is gap between SDRR and ERR, just coincidence in this example comparison

now the difference between this Grendel vs .223 don't look very big, it appears we had similar enough penetration depths and we're 200 fps apart on impact velocity, and even somewhat similar in SDRR/ERR rates, though The Grendel dumped 66.7 ft/lbs per inch vs the 36.3 ft/lbs of the .223 and retained 81% bullet weight vs 39%

please don't take the above data as me saying one is better than the other, I'm not, too early in the game for that imo, there's argument that peak efficiency lies in where the bullet essentially finishes offside hide with zero retained weight meaning ALL potential work landed perfectly in distance we wanted it too, so potentially the the lack of weight retention percentage in the .223 is actually a measure of higher terminal efficiency and is what explains the unusual amount of internal damage that defies our current standards of understanding?

 

[Formidilosus]

I didn’t want to hijack the .223 thread any further with where I’d like to go with the key minds on modern terminal ballistics here at Rokslide.

Did you read the entire thread? The info about actual terminal ballistics and how it’s measured are in there.

• The in-flight ballistics we’ve got down pat, all the right numbers, measures and thorough understanding of it all. We’re able to maximize the peak potential of our rifles and gear now to levels never even talked about 15 years ago for most.

Yes, because they shot bullets into an environment, and measured the flight. Same as-

• The terminal ballistics we don’t have quite to the same level. This is the topic we still argue the most about as a whole, still have too many gaps, lack of potential measures, and it’s a subjective mess for most of the discussions…IE; 67 pages on the .223 thread.

Incorrect. There are two components- psychological and physiological. The physiological component of terminal ballistics- that is measuring amount of tissue damage caused by the passage of a projectile is extremely well known, and has been sine the early 90’s. There is no magic. There is no math equation. Shoot bullets into tissue or properly calibrated tissue simulate and measure the physical damage created. Do it at different impact velocities.

So hoping we can narrow the gap between the two further with this thread. It feels like many of us can see/understand/feel and explain reasonably well a different level of understanding but it’s still a muddy experience in most discussions. Lots at play from trying to break down old, institutionalized 20th century info like ‘just throw a 180 from a 30 and you’re fine’ to the 21st century understandings we are gaining now. I feel like we’re on the cusp of a bit of an evolutionary curve here on the terminal side of things.

Not trying to be rude, but the “cusp” was in 1989.

I’ve had some thoughts around this for awhile and started to put things on paper early in 2020. Trying to find ways to level this playing field, are there measures we are missing and could be working on to help explain things more objectively? I’ll give an example of where I’ve started to go here…. (SNIP)

You’re trying to describe “math based metrics”. Every single version you can come up with has been tried repeatedly, medically tested in labs, and utterly failed.
“Damage based metrics”- that is measuring the actual wound created by the passage of a bullet has repeatedly and consistently been the only thing that has legitimate correlation to “killing”.

So in my mind there’s measurable information there we aren’t talking about yet. There are delta’s between the start of that 17” of travel and finish…those numbers aren’t currently being discussed at this point, let alone applied. There’s no current system of factory standards to measure these things so we are going to be using inconsistent mediums of ‘game’ at this point to help illustrate future potentials.

That is incorrect. The “delta” between starting and finishing are called “total penetration depth” (Pen), “permanent crush cavity” (PC), temporary stretch cavity” (TC), “depth to max TC”, and “neck length” (NL).

For a long time I thought ft/lbs was a useless measure, and maybe that will still prove true?, but after working some of this out in my mind I feel like maybe there is a way to incorporate ‘energy’ into the equations to help explain that internal work. My main formula is still primarily ‘for game intended’ matching SD, with construction, and impact velocity…get that right and there’s magic.

Ft-lbs energy is a useless metric for twmrinal ballistics, has no bearing or information on penetration depth, wound channel size or shape- nor could it tell you those things.

There is a magic formula but we don’t have the best data or measures to explain that yet. Maybe better measures are thought of during this discussion?

I would highly suggest you Google and read papers and studies by-

Dr Martin L. Fackler
Gary K. Roberts
FBI Ballistics Lab
Etc.



This- Terminal Ballistics History Overview can be a starting point.

 

[Stinky Coyote]

haha ok, there is also the possibility that the first guy through the wall always gets bloody right? willing to slow this down a bit and absorb and discuss rather than react?

if we had this well sorted there wouldn't be thread after thread of subjective thoughts on it and where's the neat little graph or chart to accompany factory ammo to 500 yards that explains what happens after the bullet gets there?

this is the 21st century, we can do better than what we currently have or we wouldn't still have threads like the .223 thread

it wouldn't be the first time I was a little 'too much too soon' in my thoughts lol but what would your simplified ammo box chart look like then to explain this, what measures to use?

you're saying there's no measurable potential post impact on the bullets that can be further studied and defined? to provide more objective information? I ain't buying it, don't be an old dog that can't be taught new tricks, you've had plenty of experience with doing that to old dogs I'm sure, same here, it'll take some humility to ensure we don't end up becoming old dogs ourselves...this doesn't need to be a measuring contest, lets work out some thoughts not dismiss them trying to dismiss a messenger that may have come in awkwardly hot and rubbed someone the wrong way

is what I'm saying challenging something you've been putting out for awhile? I don't think we disagree on much in this really and see it very similar or we wouldn't be out there hammering with sub 30 grains of powder...question I have is can we remove egos and move things forward on this end for the greater good?

my end vision is if this is achievable, then that give manufacturers entirely new directions to advance towards in bullet technology and then everything that will go into the headstamps behind those bullets, we agree the bullet is the most important part but my contention is we have 20th century measures to show what happens post impact and that something could be standardized to propel things to the next levels

and bear with me, I'm gonna try the multi-quote thing you seem to have down pat...have some thoughts on your thoughts, slow down

 

[Stinky Coyote]

Did you read the entire thread? The info about actual terminal ballistics and how it’s measured are in there.

Read it, still went 67 pages over 2 years didn't it. Looking for that chart version.

Incorrect. There are two components- psychological and physiological. The physiological component of terminal ballistics- that is measuring amount of tissue damage caused by the passage of a projectile is extremely well known, and has been sine the early 90’s. There is no magic. There is no math equation. Shoot bullets into tissue or properly calibrated tissue simulate and measure the physical damage created. Do it at different impact velocities.

That's what I'm saying here, you think that because it hasn't been figured out yet that it's not possible? Well I disagree and say you are incorrect, look how far we've come so far, breakthrough 1990 you say, what about another in 2020? You wanna be a part of it or just say no I'm an old dog now, no new tricks for me?

Not trying to be rude, but the “cusp” was in 1989.

Well it appears we will have issues with who can out a-hole the other here. Not really what I wanted to do here as you have a lot of great experience with what I want to talk about. Your's is bigger...happy now?

You’re trying to describe “math based metrics”. Every single version you can come up with has been tried repeatedly, medically tested in labs, and utterly failed.
“Damage based metrics”- that is measuring the actual wound created by the passage of a bullet has repeatedly and consistently been the only thing that has legitimate correlation to “killing”.

Again, breakthrough in 1990 was the last breakthrough we will have in this highly subjective topic? None of that sounded very objective to me.

That is incorrect. The “delta” between starting and finishing are called “total penetration depth” (Pen), “permanent crush cavity” (PC), temporary stretch cavity” (TC), “depth to max TC”, and “neck length” (NL).

What if the delta you are referring to is so '20th century' understanding? What if we could math this shizzo out better in the 21st? Why so quick to react or shoot this discussion down? Nothing objective about 'crush cavity, temporary stretch, lol. We could come up with better, more objective ways to look at this now, you help would be great.

Ft-lbs energy is a useless metric for twmrinal ballistics, has no bearing or information on penetration depth, wound channel size or shape- nor could it tell you those things.

I largely agree with this and fought it so for ages, however, it is currently measurable number that we are discussing but is there an objective view/correlation or possible link to help explain that subjective 'temporary stretch/permanant crush' that we just haven't seen yet?

So gonna have to ask at this point that we try to see if we are missing something here and if there are measures that would could FORSEE that could one day become measures we converse and understand like SD, BC, FPS, KE etc.???????? We are like 98% there in-flight...but feels like we're about 50% there when the swimming starts.

If it's too soon to go there just say so, I think you're saying so...but I disagree. I wanna see the next level of tech that could come from getting this more objectively understood and measured.

my mind has absorbed plenty of what's out there over the decades, been staring at ballistics tables since I was 12, not professing to be anything here or puffing my chest, my mind seems to go where I can't find the information, or is there better ways to explain what we see once the knife comes out? outside the box, like many of the sources you will cite will have also done, we don't have to rehash what we already 'know', lets go somewhere different and challenge ourselves a bit here, seems like a safe forum and safe thread to get a little outside the box to me?

 

[Formidilosus]

haha ok, there is also the possibility that the first guy through the wall always gets bloody right? willing to slow this down a bit and absorb and discuss rather than react?

I have no idea what you are implying or getting at. I have no ego invested in this, or anything else. I’m giving you reality that can be tested, measured and observed. I gave you starting points to read and understand that just like external ballistics, terminal ballistics is a known thing.

if we had this well sorted there wouldn't be thread after thread of subjective thoughts on it

There are threads after threads on it because people have no clue that the information is out there, and most- like you seem to be doing, refuse to realize that it’s already done. There is no magic. It has been tested and proven for 30 years.

and where's the neat little graph or chart to accompany factory ammo to 500 yards that explains what happens after the bullet gets there?

You can’t have a “chart” on a box of ammo unless it’s pictures of the wound channel at multiple velocities. Or, the information about NL, Pen, PC, TC, max TC, etc.

this is the 21st century, we can do better than what we currently have or we wouldn't still have threads like the .223 thread

Again- the information is publicly available. I gave you days worth of reading by a Google search.

it wouldn't be the first time I was a little 'too much too soon' in my thoughts lol but what would your simplified ammo box chart look like then to explain this, what measures to use?

Stop worrying about a thing like a “game rating” on a box. Educate yourself.

you're saying there's no measurable potential post impact on the bullets that can be further studied and defined? to provide more objective information?

There is a lab who’s almost sole function is to measure and validate terminal ballistics year round, with nearly every projectile made. It is constant. Terminal ballistics is not complicated. It is simple and once it was figured out what physiological damage is caused by the passage of a projectile- no, there is not much more to be defined in terminal ballistics until a radically different technology for wounding comes about.

I ain't buying it, don't be an old dog that can't be taught new tricks, you've had plenty of experience with doing that to old dogs I'm sure, same here, it'll take some humility to ensure we don't end up becoming old dogs ourselves...this doesn't need to be a measuring contest, lets work out some thoughts not dismiss them trying to dismiss a messenger that may have come in awkwardly hot and rubbed someone the wrong way

Again, I have no idea what you are implying. I do not care about what you believe, I do not care about personalities. I have spoken only about objective, provable, repeatable facts.

You are like an uncontacted indigenous person from the rainforest that gets an idea for a propelled means of movement using round rocks, who then walks out and sees vehicles in 2021- yet is refusing to believe that motor vehicle transportation is a thing.

 

[JFK]

You are like an uncontacted indigenous person from the rainforest that gets an idea for a propelled means of movement using round rocks, who then walks out and sees vehicles in 2021- yet is refusing to believe that motor vehicle transportation is a thing.

I have no idea what this thread is about, but this right here is funny!

 

[Stinky Coyote]

Form, I'll get to reading your suggestions here. Pretty sure I'll have absorbed that a couple decades ago and forgot most of it but keeping the relevant info at hand lol. One question as I glaze over them also not talking about what I'm looking for here is...

Are they just discussing the gel damage...or do they discuss the bullets themselves as a way to link the damage between the two?

As in, we choose the bullets first and recognize that's the smart play...but somehow the finished result of the bullet can't also tell us the story?

You saying I'll find objective measures relating to the bullets that will tell the story vs this 'NL, Pen, PC, TC, max TC, etc.' being passed off as objective measurable information imo. Seems to really be helping our current discussions along nicely and everyone understands it perfectly. Why aren't all bullets then compared to each other to show the potentials to the would be masses of consumers?

As for the bandwagon guys who wanna see a dual, and their favourite character win, relax, it'll be a dual I guess so you'll be entertained although I was hoping for more of an open minded collaboration, if one guy just wants to cite 30 year old info and views as the end of the discussion maybe he should move along as the old dog now? Clearly not the discussion for him, will however keep the subject in focus and not off in the ditch discussing the useless weeds as most of these discussions tend to end up doing.

So rather than suggest I just crawled out of the bush and can't keep up maybe consider it could be the other way around and I'm trying to lead y'all to water but can't make you drink it so there's a process at play? It could be that too ya know.

Getting after the messenger instead of the message is a lot more fun for some, we can do both, skin is plenty thick.

New concepts and discussion differences, not interested in discussing 30 year old concepts and understandings, great work, give it all its due props. Forward looking here, better easier ways to see this from hide to hide.

HAS ANYONE ELSE got some thoughts around future terminal ballistics to add to this or will it just be a measuring contest?

 

[Stinky Coyote]

You are like an uncontacted indigenous person from the rainforest that gets an idea for a propelled means of movement using round rocks, who then walks out and sees vehicles in 2021- yet is refusing to believe that motor vehicle transportation is a thing.

you are missing the point completely, not the thread for you, too much too soon, case in point...we both shoot sub 30gr powder cartridges with a very similar bullet formula, we know what to expect and we do it for a reason and from experience, we do the same thing and you want to imply I do the opposite? or I just fluked out to coming to the same place? lmfao man, be better, read better

you make a great student no doubt, you can recite this stuff like a rockstar, me maybe not the best student then, too many questions I guess

 

[Stinky Coyote]

maybe I can simplify this now for the rest of those who might be interested

bullet in air - check - we got this

bullet meet hide and start swimming...we don't got this simplified to the same understandings/measures/levels

hide to hide, bullet starts, bullet ends, two very measurable parameters, even currently, SD/BC, Retention, Energy, Velocity then we got what happens in the soft stuff...and the question I'm looking to find answers here where there's lots of guys who push the limits on discovering potentials etc. on all this...is....can we better connect, from the bullet itself, what we can predict will happen between hide to hide under certain chosen control factors (impact velocity/medium etc.)

that simplifies our abilities to choose for the masses?

come on...we can do better than how we are currently doing it

sounds like the bulk of the work is just discussing the weeds in the middle ignoring something that could be much more objective?

anyway, here's a thought and maybe a table would help this visualization but maybe extremes are the way to see this to get my asks here?

lets take a .257 Weatherby 80gr ttsx vs a .223 77gr tmk to illustrate this further...

by looking at the recovered bullet from a control medium we might see a few numbers that could show us why the bee will go through 4' of critter if driven hard enough but impart very little damage along the way vs the opposite end of the spectrum going through 18" of medium dumping quite a bit more damage over a shorter path

it's a bit of a brain screw wrapping head around how to see all the possible measures but my contention is they are available nonetheless and with the right table and a couple new measures of viewpoints we could see this so much easier than the current cited talk about the far more subjective current path of of what happens along the way

we can measure final sd, we can measure upset over distance, we can measure energy over distance, we can measure deltas between start and stop numbers like SD, we can come up with a better formula by looking not just at the more subjective middle travel but by the final bullet itself....we just aren't doing it yet, so I'm looking for forward thinkers and discussion on what would that math look like, I'm trying to offer some stimulating thoughts to spur this along...not argue with Form, if just regurgitating the stuff we already know then don't please, lets go somewhere new, if you don't believe we can go somewhere new then don't participate here, it can die here and we can think that's it there is nothing further to be said as it's already been said...and I'll continue to think we can explain this better, we're just not ready yet

are we just not ready yet?

wouldn't it be nice to look at a chart of bullets we can buy and compare them terminally just as we do with the in-flight and see the realistic view of what's to be expected post impact?

this is where I'm headed, what are we missing to get to that level of simplicity? I think we could solve this riddle

 

[Tmac]

From my perspective, we don’t need more formula’s or lethality numbers or what not. I’d guess 90% of most shooters problems would go away with more of the right kind of practice. Intelligent people can disagree on what we want out of a bullet, and select accordingly. In other words, more shooter work on the bullet placement part of the “equation” and better tools to help select a bullet with the performance characteristics you desire, resonate with me. The first is a personal commitment, the second is more of a challenge.

I’m fortunate in that I've had plenty of opportunity in the field on deer and elk sized game, with different bullets, to 400 yards. So within that box, I know exactly what I want and which bullets I prefer. As I extend my range, what I need out of a bullet is changing and I lack field experience there. So selfishly for me, my interest lies more in comparisons between bullets. With quite a bit of study, I found what I need. Had a single source been available, like we have with a chart on powder burn rates, it would have gone quicker.

So for me, there would be value in some sort of standardized bullet performance data base of the terminal phase. If it exists, I missed it. Select a standardized medium to test the terminal phase and then use all commonly used bullets to develop a bullet performance base at 3-4 impact speeds. I have seen many bullet tests, but usually a small sample size and then another source tests with slightly different media. Be time consuming and $$$. Basically more similar to some of the testing done by Cal on the Precision Rifle Blog, but done on the terminal phase. I’d be more inclined to see value in apples to apples vs all the slightly different tests. All that said, there is lots of actual data out there. With social media, we have more and more real world examples easily available, just takes some looking around.

I‘ve read Frackler and also recall a guy using dead goats in a jig, forget his name. But again, what I found was more scattered, test criteria were all different, etc. My two cents anyway.

 

[TreeStandAthlete]

From my perspective, we don’t need more formula’s or lethality numbers or what not. I’d guess 90% of most shooters problems would go away with more of the right kind of practice.

Amen to that brother. I see lots of parallels to the EFOC crowd on the archery side. Spending months arguing about mathematical formulas and applied physics to fix a problem that they could've solved by pulling their bows out a little more often and actually learning to shoot.

Not targeted at anyone, just a general observation.

Sent from my SM-G996U1 using Tapatalk

 

[Stinky Coyote]

Tmac and Treestand Athlete...getting good at running what you brung always trumps everything. Bad hits are bad hits and not much short of a bazooka will save the day so placement trumps all.

For the go forward here lets remove that part from the discussion and just assume we're gonna place it.

Agree on archery side, got into that a fair bit also but you can actually look at that from the SD side of things much like we do with things currently with bullets. You just have to envision the arrow as just a funny shaped bullet is all. 125gr tip on the same diameter shaft and same diameter cuts vs a 100 gr is going to have a higher SD so it will go deeper. But SD isn't really used as it would be hard to figure out on an arrow lol. Same thing is at play however. Also, the SD remains the same, like a solid bullet, so in that respect it's easier to compare. Same cut, same drag, but higher SD will penetrate slightly deeper out of the same bow as they often collect a bit more ke from the bow to start with(ie; I'd shoot a 350 gr out of my bow at x-speed and x-ke but throw a 475 gr arrow out of it and yup its slower but grabbed a couple more ft/lbs ke) but same impact velocity the heavier always goes deeper given same sd.

And Tmac, I totally agree with trying to develop a comparator or new calculator that we can compare bullets by on the terminal side...we have enough calculators that show us what happens on the in-flight side of things. Just a couple crude numbers to understand what will happen after and lots of subjective input to go with (our experience/word of mouth etc.).

So, I know we haven't solved this riddle yet otherwise manufacturers would have calculators for this figured out. New terms/measures that would come with their bullets as inputs (possibly like SDRR or ERR) etc. and that's the point of this conversation. If they had calculators like this it would spur development of bullet design that gives better 'numbers' in this regard. Ie; if guys want to start maximizing 3' penetration potential and want 3x expansion and x-amount of energy dump per inch...they could play with the bullets available and speeds they need to impact to get their desired goals....just like we do with in-flight ballistics. We'd then see all the bullets we already know and love how they stack up to other existing bullets and new ones that hit the market from said development. Maybe a guy would need to figure out what bullet will go deepest from a current cartridge owned so he runs them all through the calculator and comes up with a barnes at the expense of it only opening 1.2x expansion and therefore producing as sad wound channel, ideal for when you need things to die on the neighbours land? Joking aside most of us would be looking for things in that 2.5x expansion range and 2' penetration potential inside a certain velocity range but having the ability to figure all this out without arguing online would be nice.

We could ultimately compare within same caliber like a .17 running 20gr max at 4000 and why it will only go 4" and lightning death and the same bullet at 2000 will go 12" and maybe a 50 yard runner? Or a 1000 gr .750 cal solid at 2000 fps vs 1000 fps should we want to compare things for an upcoming African trip? Many of us can visualize many of these scenarios but that's the point of this discussion. We haven't we got tools that can make this entirely more objective? We should have a calculator that will tell us via inputs from the manufacturer what to expect for expansion ratio, penetration depth, and energy dump ratio, maybe an efficiency percentage of some sort etc. from predetermined standardized testing of bullets so we can forward development but also choose best bullets for the jobs as consumers rather than argue like we're in the 20th century still. The manufacturer inputs of SD and BC will not be enough for this new calculator.

So what math gets us to these formulas? I believe the answer lies in the bullet at the end of its journey, not stretch/permanent anythings, well the majority of that answer is there. Goats will not be a good test medium to create this comparator lol, that's sort of how we've been doing it all this time, looking for 21st century option to compare now, it will cut down on the internet fun but it'll be more useful to bring this ability to the 21st century and then develop things for the next century. Heck we could end up killing elephants off 25 grains of powder one century perhaps due to the advancements in development? lol

 

[Castle Rock]

Jesus wept

 

[Tmac]

Tmac and Treestand Athlete...getting good at running what you brung always trumps everything. Bad hits are bad hits and not much short of a bazooka will save the day so placement trumps all.

For the go forward here lets remove that part from the discussion and just assume we're gonna place it.

Agree on archery side, got into that a fair bit also but you can actually look at that from the SD side of things much like we do with things currently with bullets. You just have to envision the arrow as just a funny shaped bullet is all. 125gr tip on the same diameter shaft and same diameter cuts vs a 100 gr is going to have a higher SD so it will go deeper. But SD isn't really used as it would be hard to figure out on an arrow lol. Same thing is at play however. Also, the SD remains the same, like a solid bullet, so in that respect it's easier to compare. Same cut, same drag, but higher SD will penetrate slightly deeper out of the same bow as they often collect a bit more ke from the bow to start with(ie; I'd shoot a 350 gr out of my bow at x-speed and x-ke but throw a 475 gr arrow out of it and yup its slower but grabbed a couple more ft/lbs ke) but same impact velocity the heavier always goes deeper given same sd.

And Tmac, I totally agree with trying to develop a comparator or new calculator that we can compare bullets by on the terminal side...we have enough calculators that show us what happens on the in-flight side of things. Just a couple crude numbers to understand what will happen after and lots of subjective input to go with (our experience/word of mouth etc.).

So, I know we haven't solved this riddle yet otherwise manufacturers would have calculators for this figured out. New terms/measures that would come with their bullets as inputs (possibly like SDRR or ERR) etc. and that's the point of this conversation. If they had calculators like this it would spur development of bullet design that gives better 'numbers' in this regard. Ie; if guys want to start maximizing 3' penetration potential and want 3x expansion and x-amount of energy dump per inch...they could play with the bullets available and speeds they need to impact to get their desired goals....just like we do with in-flight ballistics. We'd then see all the bullets we already know and love how they stack up to other existing bullets and new ones that hit the market from said development.

We could ultimately compare within same caliber like a .17 running 20gr max at 4000 and why it will only go 4" and lightning death and the same bullet at 2000 will go 12" and maybe a 50 yard runner? Or a 1000 gr .750 cal solid at 2000 fps vs 1000 fps should we want to compare things for an upcoming African trip? Many of us can visualize many of these scenarios but that's the point of this discussion. We haven't we got tools that can make this entirely more objective? We should have a calculator that will tell us via inputs from the manufacturer what to expect for expansion ratio, penetration depth, and energy dump ratio, maybe an efficiency percentage of some sort etc. from predetermined standardized testing of bullets so we can forward development but also choose best bullets for the jobs as consumers rather than argue like we're in the 20th century still. The manufacturer inputs of SD and BC will not be enough for this new calculator.

So what math gets us to these formulas? I believe the answer lies in the bullet at the end of its journey, not stretch/permanent anythings, well the majority of that answer is there. Goats will not be a good test medium to create this comparator lol, that's sort of how we've been doing it all this time, looking for 21st century option to compare now, it will cut down on the internet fun but it'll be more useful to bring this ability to the 21st century and then develop things for the next century. Heck we could end up killing elephants off 25 grains of powder one century perhaps due to the advancements in development? lol

I don’t think the answer is a new calculator. Be very difficult to come up with an algorithm that accounts for all the variables, I think anyway. Speed, bullet construction, different media, etc. Were I were to tackle the topic, it would be with actual bullet impacts in a standardized media and extrapolate from there, probably. But right now, I have what I need, I just need to apply it in the field, 400-600 yards or so.

 

[Stinky Coyote]

I don’t think the answer is a new calculator. Be very difficult to come up with an algorithm that accounts for all the variables, I think anyway. Speed, bullet construction, different media, etc. Were I were to tackle the topic, it would be with actual bullet impacts in a standardized media and extrapolate from there, probably. But right now, I have what I need, I just need to apply it in the field, 400-600 yards or so.

I agree this would be an undertaking to develop further but it's the gap that needs to be filled imo, for consumers and manufacturers who like to go forward in development. And quite frankly being 2021 and where we're at understanding inflight ballistics we should be further ahead with the terminal side imo, so it's just time get this party started imo.

I know right?, which medium will show best, which impact velocities to choose, or one standard for each family of cartridges perhaps? What math/measures we aren't talking about yet like finished SD/Weights/Expansion/Reduction Ratio's etc.???

I'm living in same world as you, used to build 800+ yard rigs etc. now I'm happy with a 16" Grendel and 400-ish for big game and can dial up to 600 for coyotes and target fun, possibly deer to 500 on the extreme end. Figured out I didn't need to burn more than 30 grains of powder to do what I want/need now. Now guys are burning less with that .223 and I think it's great that there's all that data but that's tough to explain to people...the calculating ability I'm talking about would make that a lot easier to explain by providing just the link lol. They can plug in their ole 30 cal chuckin a 180 numbers and compare to some of this new stuff and see why and how it works.

What I'm curious is for those into this...what ideas or maths or numbers would you envision need to be figured out to build this ability out for the future?

 

[JohnnyB]

V(3.27* p-ve2)/1.19{5+ft3}+.33*69< aim small, miss small

 

[ARK_Ginger]

HAS ANYONE ELSE got some thoughts around future terminal ballistics to add to this or will it just be a measuring contest?

The future of terminal ballistics is the way Hornady TAP line of ammunition is advertised with ballistic gel data included. There will not be a convenient equation to produce a number to compare bullets with that can accurately describe what the bullet does terminally.

I would also wager that it's not profitable for manufacturers to start providing ballistics gel data for each round they sell. Why? How would they sell magnums and new wizbang cartridges when the ballistics data shows that a 77gr TMK will kill nearly everything in North America? What you're asking for would require a third party to test every bullet at the FBI standard (I assume) and have that data available for the informed consumer. I'm of the opinion that that endeavor is not profitable enough which is why it hasn't been done publicly yet.

 

[ARK_Ginger]

I'll also add that I believe manufacturers are very aware of how their bullets perform terminally. They also know what markets and sells well. Unfortunately that tends to be a picture of a perfectly mushroomed bullet instead of mush vitals.

 

[Shraggs]

Stinky I kinda get where your coming from. The 223 thread was such a head scratcher to me, I’m older and knew conventional wisdom where some of these metrics, tried, to explain lethality. Seriously, 22 with low sectional density kills elk at near quarter mile with dramatic empathy!

Long before I joined here in my quest, I stumbled and have book marked and read everything form posted above. 35 cal had good data too. As I got into forums, I read statements of facts from high posters that weren’t consistent with white papers.

I think it’d be more or equally useful to document the already known wounding profiles for projectiles, by type, caliber, a speed range of usefulness - instead of a predictive method or formula, since this data is known.

I guy then could better understand choices.

“ I own x caliber, my current skill is a few hundred yards, want to hunt elk. I see many cup and core options are sufficient, as well as a few what they call bonded bullets, let search for some these to buy”

Or “ I’m proficient with x caliber to 400 yards, as I stretch my distance for elk are better options than these federal fusions for this smallish caliber”.

Idk, good for thought. I’d help ya