Proposed change for range affect on damage

[mmartin798]

Originally Posted by Desert Mariner

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]

Originally Posted by mmartin798

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]

Originally Posted by Desert Mariner

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

[Desert Mariner]

Originally Posted by nuke11

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.

[nuke11]

Originally Posted by 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

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]

Originally Posted by nuke11

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]

Originally Posted by 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.

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.

[mmartin798]

Originally Posted by 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.

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.