Proposed change for range affect on damage

[mmartin798]

On page 88 of the 4th edition rules there is a section entitled "Range Effects on Damage" which outlines how E-factor diminishes with range. In short, the rule states that damage falls by 1 for every multiple of effective range. As is often the case, this didn't sound right, so I went to the spreadsheet and plotted the rule against the results from GNU Ballistics for three different rounds. The results are shown in the top picture entitled "Range vs EFactor-Current". The rule results are plotted in green while the GNU Ballistics results are in blue. It is pretty obvious that they do not match up very well. Also, contrary to the rest of text in the "Range Effects on Damage" section of the rules, the heavier rounds were not necessarily affected more. The lightest round in the sample was the 5.56mm. If you look the 9mm is much flatter than the 5.56mm showing the exact opposite of the regarding mass of the round. Fortunately this rule has a relatively easy fix, but to understand it, the GNU Ballistic plots need to be looked at in more depth.

If you look at both the 5.56x45mm and 12.7.99mm rounds, the pattern of the blue dots in both cases is very much a hockey stick. The 9x19mm is pretty flat. That is because the speed of sound is about 1100 f/s. That almost the initial velocity of the 9x19mm round. Looking at the 5.56x45mm and 12.7x99mm rounds the point where the curve flattens out happens around a velocity of 1100 f/s as well. From this we can assume that it is the faster than sound velocity that dramatically increases the drag. Again, comparing the 5.56 and 12.7 we see that the velocity drops to sub-sonic after about 2 multiples of the effective range and that the damage drops by about 1/3 of the range zero EFactor. This is a good start.

Looking at the 9x19mm plots, the rules drop off damage much too quickly. You get a much better fit if you drop the damage by 1 every 2 multiples of effective range.

Combining these two new findings to the rules column and plotting them against the GNU Ballistics result gives the results you see in the bottom picture entitled "Range vs EFactor-Proposed". These curves match up much better and the rules are still easy to apply.

[ArmySGT.]

How does it work out for cartridges that start out as subsonic? .45, .300, .458 SOCOM, black powder muzzle loaders; for example.

[mmartin798]

How does it work out for cartridges that start out as subsonic? .45, .300, .458 SOCOM, black powder muzzle loaders; for example.



Without running additional ballistic plots, I would assume it runs like the 9x19mm, where the EFactor would drop off by 1 for every 2 multiples of effective range.


Sent from my iPhone using Tapatalk

[nuke11]

To "simplify" this, I started to provide range charts to the players for each of their weapons used.

I use a program called Ballistics Explorer v6.50 (an online site to use is http://www.shooterscalculator.com/).

Since we know the muzzle velocity of each weapon, I just find a cartridge that is approximate to the issued ammunition in the DB and plot a chart out to 1000 m for rifles/LMG, 1500 m for MMG, 2000 m for HMG and 200 m for pistols/SMG's at 50 m intervals.

They look similar to your Excel charts you show. I give distance, velocity, energy, time of flight and e-factor.

[mmartin798]

To "simplify" this, I started to provide range charts to the players for each of their weapons used.

I use a program called Ballistics Explorer v6.50 (an online site to use is http://www.shooterscalculator.com/).

Since we know the muzzle velocity of each weapon, I just find a cartridge that is approximate to the issued ammunition in the DB and plot a chart out to 1000 m for rifles/LMG, 1500 m for MMG, 2000 m for HMG and 200 m for pistols/SMG's at 50 m intervals.

They look similar to your Excel charts you show. I give distance, velocity, energy, time of flight and e-factor.

I considered this approach, like I did for whole body damage from explosives, but thought a separate chart for each weapon may not be as desirable as an algorithm.

[ArmySGT.]

What do you think of positive or negative to hit modifiers for range?

Bullet rise and the bullet drop haven't been incorporated into anyone's tables to my knowledge.

[mmartin798]

What do you think of positive or negative to hit modifiers for range?

Bullet rise and the bullet drop haven't been incorporated into anyone's tables to my knowledge.

So something different than the current range modifiers. Not sure how to tie that to ballistics plots.

[nuke11]

MMARTIN798;

Did you ever finish this, or did I miss a file you provided?

[mmartin798]

You didn't miss anything. I just ran a sampling of ballistic plots to see if I could get an approximation using an algorithm of the actual results that matched up better than the overly simple rule in the book. I never did make an extensive spreadsheet of range charts. Though recently I have been considering it for use in a game aid. Basically laminated cards with a stat block, picture of the weapon, and a section to mark off rounds as you go with a dry or wet erase marker that would have the range card on the back. That also has not gotten beyond a basic mock-up of the card that needs revising.

[nuke11]

You didn't miss anything. I just ran a sampling of ballistic plots to see if I could get an approximation using an algorithm of the actual results that matched up better than the overly simple rule in the book. I never did make an extensive spreadsheet of range charts. Though recently I have been considering it for use in a game aid. Basically laminated cards with a stat block, picture of the weapon, and a section to mark off rounds as you go with a dry or wet erase marker that would have the range card on the back. That also has not gotten beyond a basic mock-up of the card that needs revising.

Ok, I'll have to have a look and see what I can figure out.

I do like that idea of cards thou.

[mmartin798]

Hypothetically, if I were going to spend a few hours to generate the range charts for all the 4ed weapons, would it be safe to say all the pistols use G1 drag coefficient and all rifles use G7 drag coefficient? Otherwise, where would you suggest finding the appropriate coefficient to use? I would not use any atmospheric corrections, as those are way too situational.

[nuke11]

Hypothetically, if I were going to spend a few hours to generate the range charts for all the 4ed weapons, would it be safe to say all the pistols use G1 drag coefficient and all rifles use G7 drag coefficient? Otherwise, where would you suggest finding the appropriate coefficient to use? I would not use any atmospheric corrections, as those are way too situational.
G1 for pistol is fine and G7 is fine for rifles. Most military rifle ball ammunition is boat tailed.

Using these will make short work on any calculations you perform.

[Desert Mariner]

Hypothetically, if I were going to spend a few hours to generate the range charts for all the 4ed weapons, would it be safe to say all the pistols use G1 drag coefficient and all rifles use G7 drag coefficient? Otherwise, where would you suggest finding the appropriate coefficient to use? I would not use any atmospheric corrections, as those are way too situational.

The actual coefficients are normally listed on the box and/or in the manufacturer's literature. I started a similar exercise not too long ago and the first decision to be made is what specific cartridges to use. I ended up using cartridges from Sellier & Bellot (S&B) since they didn't have an overwhelming number and they provide the needed info (BC, V0 with test barrel length, projectile weight, etc.). Even this small selection provided 6 normal 9mm loads plus 2 subsonic 9s. I then computed the MV for each weapon with the selected cartridge. Picked an on-line calculator (Berger Bullets as it is simple) and set up an Excel sheet to import the generated data. The attached PDF is what I generated for 4E weapons (shotguns are not included as I'll need separate range charts for slug and shot).

Range cards for pistols run 10-200m at 10m increments, sub guns run 20-400m at 20m increments and rifles/MGs run 50-1000m at 50m increments. Some of these probably need adjustment. E-factor for each range is calculated from the listed velocity for the range. Cartridge used is listed on the range card as well so that anyone can recreate a chart at different ranges if they so desire.

I'm currently giving the same treatment to some updated weaponry but there doesn't seem to be much interest in the other thread I posted in.

[nuke11]

The actual coefficients are normally listed on the box and/or in the manufacturer's literature. I started a similar exercise not too long ago and the first decision to be made is what specific cartridges to use. I ended up using cartridges from Sellier & Bellot (S&B) since they didn't have an overwhelming number and they provide the needed info (BC, V0 with test barrel length, projectile weight, etc.). Even this small selection provided 6 normal 9mm loads plus 2 subsonic 9s. I then computed the MV for each weapon with the selected cartridge. Picked an on-line calculator (Berger Bullets as it is simple) and set up an Excel sheet to import the generated data. The attached PDF is what I generated for 4E weapons (shotguns are not included as I'll need separate range charts for slug and shot).

Range cards for pistols run 10-200m at 10m increments, sub guns run 20-400m at 20m increments and rifles/MGs run 50-1000m at 50m increments. Some of these probably need adjustment. E-factor for each range is calculated from the listed velocity for the range. Cartridge used is listed on the range card as well so that anyone can recreate a chart at different ranges if they so desire.

I'm currently giving the same treatment to some updated weaponry but there doesn't seem to be much interest in the other thread I posted in.

Nice, I like them.

The only problem I see is the name of the Uzi carried over from the book. The Uzi No2 Mk B was a civilian version with a 16' barrel imported into the US from 1983 to 1989 and most where semi-auto only. It is not what would be considered "cool" to have in TMP as a player. Just the Name of Uzi is fine.

[mmartin798]

The actual coefficients are normally listed on the box and/or in the manufacturer's literature. I started a similar exercise not too long ago and the first decision to be made is what specific cartridges to use. I ended up using cartridges from Sellier & Bellot (S&B) since they didn't have an overwhelming number and they provide the needed info (BC, V0 with test barrel length, projectile weight, etc.). Even this small selection provided 6 normal 9mm loads plus 2 subsonic 9s. I then computed the MV for each weapon with the selected cartridge. Picked an on-line calculator (Berger Bullets as it is simple) and set up an Excel sheet to import the generated data. The attached PDF is what I generated for 4E weapons (shotguns are not included as I'll need separate range charts for slug and shot).

Range cards for pistols run 10-200m at 10m increments, sub guns run 20-400m at 20m increments and rifles/MGs run 50-1000m at 50m increments. Some of these probably need adjustment. E-factor for each range is calculated from the listed velocity for the range. Cartridge used is listed on the range card as well so that anyone can recreate a chart at different ranges if they so desire.

I'm currently giving the same treatment to some updated weaponry but there doesn't seem to be much interest in the other thread I posted in.

I just want to point out that in the Berger Bullets ballistics calcultator, you still need to select the curve set. Looking at the presets, the pistol rounds use G1 and the rifle rounds use G7.

[Desert Mariner]

I just want to point out that in the Berger Bullets ballistics calcultator, you still need to select the curve set. Looking at the presets, the pistol rounds use G1 and the rifle rounds use G7.

Keeping it simple, the answer is yes. But bear in mind G7 actually is dependent on the bullet (7.5 degree BT) not the weapon so in some instances a rifle may need to use G1.

In my calculations, if the BC is clearly labeled by the manufacturer as G7 I used it. If there was any doubt (i.e. only one listed), I assumed it was a G1 BC. Luckily, most manufacturers (S&B included) list both and G1 works in a pinch as the two curves usually run close to each other.

[Desert Mariner]

My apologies, the original PDF I posted was an older version. This one identifies the type of BC used (G1 or G7) and includes photos for most of the weapons (Stoner photos seem to be few and far between).

You'll note that the 5.56 weapon's E-factors come out lower than those listed in TM-1-1. I don't know if this is an error in the 4E figures or if I just haven't found the right cartridge to bump up V0.

I've given a similar treatment to numerous weapons for possible use in the equipment updates mentioned in 4E. They range from Sig P320s in 4 sizes and calibers to the FN SCAR series, HK UMPs and USPs plus some .45 Colt revolvers and lever guns for fun.

EDIT - added the attachment that somehow didn't upload the first time

[nuke11]

You'll note that the 5.56 weapon's E-factors come out lower than those listed in TM-1-1. I don't know if this is an error in the 4E figures or if I just haven't found the right cartridge to bump up V0.


Try using Federal American Eagle .223 55 grain and 62 grain.

55 grain: BC .269
62 grain: BC .307

[nuke11]

My apologies, the original PDF I posted was an older version. This one identifies the type of BC used (G1 or G7) and includes photos for most of the weapons (Stoner photos seem to be few and far between).

You'll note that the 5.56 weapon's E-factors come out lower than those listed in TM-1-1. I don't know if this is an error in the 4E figures or if I just haven't found the right cartridge to bump up V0.

I've given a similar treatment to numerous weapons for possible use in the equipment updates mentioned in 4E. They range from Sig P320s in 4 sizes and calibers to the FN SCAR series, HK UMPs and USPs plus some .45 Colt revolvers and lever guns for fun.

EDIT - added the attachment that somehow didn't upload the first time
How much nitpicking do you want?

Example. Barrett M82A1A : "metallic sights" could read better as iron sights. They are technically metallic, but I've never heard it referred to as metallic sights.

And I see what you noted as to E-factors. Most of the time when I'm doing a range card for my players I would use the stated MV of the firearm as the starting value and use the adjust charts from the software as the range card. For firearms I couldn't find a value I would use some charts found on the internet for general lengths to MV for different types of ammunition.

[Desert Mariner]

Try using Federal American Eagle .223 55 grain and 62 grain.

55 grain: BC .269
62 grain: BC .307

Without rounding, even these calculate lower than the E=15 listed in TM 1-1:

55gr FMJ @987mps comes to E=14.5
62gr FMJBT @920mps comes to E=13.5

I'd have to treat the BC as G1 since they don't specify and that would align with other 5.56 rounds.

The S&B 5.56 rounds I've checked include (these BCs are all G7):
55gr FMJ @1006mps BC=0.143 E=14.8
62gr DIM @945mps BC=0.143 E=13.9
63gr Tracer @915mps BC=0.143 E=13.4
69gr HPBT @920mps BC=0.148 E=13.5

E-factors shown calculated based on listed MV of cartridge, they will vary when barrel length of actual weapon is included.

Side note: I have been attempting to limit the number of ammo producers in keeping with the Project's need for secrecy and to simplify logistics.

[Desert Mariner]

How much nitpicking do you want?


And I see what you noted as to E-factors. Most of the time when I'm doing a range card for my players I would use the stated MV of the firearm as the starting value and use the adjust charts from the software as the range card. For firearms I couldn't find a value I would use some charts found on the internet for general lengths to MV for different types of ammunition.

What I've done thus far is take the MV from the cartridge manufacturer and compare their test barrel length to the weapon's barrel. I then adjust the MV for the weapon by +/- 25fps per inch difference. this is a rule of thumb I was taught years ago but I have seen a figure as high as 50fps/inch in some forums.

[Desert Mariner]

I’ve often wondered about the E-factor calculation itself. Is velocity and diameter the best indicator of ballistic damage? Rules state “Projectiles cause damage by virtue of the energy transferred into the target.” So why not utilize the projectiles energy (E=0.5*m*v^2) [m=bullet mass in grains; v=velocity] as a starting point to determine E-factor? Granted I have no idea how you’d scale the result to fit the current BP/damage system.

[nuke11]

I’ve often wondered about the E-factor calculation itself. Is velocity and diameter the best indicator of ballistic damage? Rules state “Projectiles cause damage by virtue of the energy transferred into the target.” So why not utilize the projectiles energy (E=0.5*m*v^2) [m=bullet mass in grains; v=velocity] as a starting point to determine E-factor? Granted I have no idea how you’d scale the result to fit the current BP/damage system.

What we may want to have a look at is Kevin Dockery's update to the damage system he created for TMP. That system can be found here on my website http://www.thesupplybunker.net/Morrow/damage_system.zip

This was going to be included in a revision of the rules at some point, but didn't as we know.

I really haven't looked at it in years, to see what it was going to improve.

[Desert Mariner]

I think I'm happy it wasn't implemented. That is one complicated set of calcs. Probably way beyond the "average" gamer, especially today's button mashers.

[mmartin798]

I’ve often wondered about the E-factor calculation itself. Is velocity and diameter the best indicator of ballistic damage? Rules state “Projectiles cause damage by virtue of the energy transferred into the target.” So why not utilize the projectiles energy (E=0.5*m*v^2) [m=bullet mass in grains; v=velocity] as a starting point to determine E-factor? Granted I have no idea how you’d scale the result to fit the current BP/damage system.

The key here is energy transferred to the target. It is possible for a higher energy round to pass through a soft target and leave a smaller permanent wound track than a smaller lower energy round which expels all its energy into the target leaving a larger wound track.

[Desert Mariner]

The key here is energy transferred to the target. It is possible for a higher energy round to pass through a soft target and leave a smaller permanent wound track than a smaller lower energy round which expels all its energy into the target leaving a larger wound track.

I get that, but I think using energy (which includes velocity) and diameter (or cross section) rather than just velocity would have yielded a more realistic figure. However, after looking over the SOJ damage rules I see that route becomes very complicated.

[Desert Mariner]

Nice, I like them.

The only problem I see is the name of the Uzi carried over from the book. The Uzi No2 Mk B was a civilian version with a 16' barrel imported into the US from 1983 to 1989 and most where semi-auto only. It is not what would be considered "cool" to have in TMP as a player. Just the Name of Uzi is fine.

Duly noted regarding the Uzi. The attached is my current SMG/PDW line-up. Original 4E weapons have an orange header for clarity. I have separate files for MGs, Pistols & Revolvers, Rifles & Carbines and Shotguns (00 buck only thus far).

[mmartin798]

I have been looking for some terminal ballistics data for shotguns. This is the best-recorded results with well-documented methods that I have seen thus far. It is a good starting place.

http://www.brassfetcher.com/Shotguns/Maximum%20Effective%20Range/Buckshot.html

[Desert Mariner]

Another site that helps with shotgun shot ballistics:
http://www.ctmuzzleloaders.com/ctml_experiments/shot-ballistics/shot-ballistics.html

[mmartin798]

Duly noted regarding the Uzi. The attached is my current SMG/PDW line-up. Original 4E weapons have an orange header for clarity. I have separate files for MGs, Pistols & Revolvers, Rifles & Carbines and Shotguns (00 buck only thus far).

I just compared my P90 stats to yours and found a discrepancy on our E-Factors. I did some research and I think I found the source. The muzzle velocity you used, according to S&B's datasheet, was based on a 4.75" barrel. That is the length of the FN Five-seveN. The P90 has a 16.04" barrel. Looking at the specs for the SS197SR, fired from the Five-seveN has the same velocity as the S&B round. Assuming that both rounds perform similarly, fired from the P90 would have a muzzle velocity of 2100 f/s or 640 m/s. That would increase your E-Factor to 9.

The biggest source of the discrepancy though is the choice of the round. I assume the Project has access to restricted rounds like the SS190. That is what give me an E-Factor of 11.

[Desert Mariner]

The biggest source of the discrepancy though is the choice of the round. I assume the Project has access to restricted rounds like the SS190. That is what give me an E-Factor of 11.

Since that last post, I tracked down stats for the SS190. V0 = 651m/s making it 684 m/s when fired from the P90 for an E-Factor of 11, which matches your figures.

I also found an error in my Excel file where I used "round" vice "roundup" in one calculation and am in the process of rerunning all of my range cards.

EDIT (9/20/19) - The rounding error was only impacting E-Factor based on muzzle velocity. The down range values were calculating properly.