Quote:
Originally Posted by The Dark
I haven't changed it, although after looking a bit more, I may need to in order to keep high-powered rounds from being less useful. I'm mostly OK with how 5.56mmN interacts, since it only fails at long or extreme range (Dam 3, Pen 1-Nil, so at short or medium 1 die is still getting through). So an M-16 will penetrate up to 110 meters and an M4 at up to 68 meters. 7.62mmN's Dam 4, Pen 2-3-Nil is more problematic, since it won't penetrate at all. I'll need to look into some sort of mechanic for high-powered rounds. My first thought (and totally not playtested) is to give a 1 point penetration bonus for rounds that are either double the armor's value or the armor's value +2 (those are two different options), with a minimum of 1 and no change to Nils (so 1-Nil would remain 1-Nil, 2-3-Nil would become 1-2-Nil, etc). Either would allow 7.62mmN to be considered 1-2-Nil against 1 or 2 point armor, which would let it penetrate Class II up to medium range and Class I up to long range. The difference is that the blowthrough would be at either 3, 4, 5, and 6 or at 2, 4, 6, and 8 for the four classes of armor. My first inclination is to go with 3, 4, 5, 6 to keep most pistols out of the world of armor penetration.
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I think you might find the use of a round's Sectional Density rating of value here. Milano has really put in work on integrating "real world ballistics" into the game. SD is determined by the formula:
Sectional Density = bullet weight (in grains)/ [7000 X bullet diameter (in inches) X bullet diameter (in inches)].
Sectional densities range from less than 1 to more than 3 and give shooters a way to rate a bullet's performance on the four sizes of "game animal." Animals (including humans) are broken into four categories known as CPX ratings. These CPX Ratings are:
CPX-1, Varmints: These are animals up to about 50lbs. The Sectional Density used should be above 1 and up to 2.
CPX-2, Medium Game: These include larger sized game that is "thin skinned" up to about 250lbs. Humans are CPX-2 and a Sectional Density around 2.5 is considered a very good "stopper" for a man.
CPX-3, Large Game: These include still larger sized game such as bear, moose, or certain African big game. These animals REQUIRE a bullet with a Sectional Density above 3 for it to be effective in stopping CPX-3 game.
CPX-4?, Dangerous Game: This list includes the largest of the dangerous game. Rhino, Elephants, and Hippo's all fall into this category and a bullet should have a Sectional Density of around 3.5 to ensure a lethal hit on these animals.
You could use the sectional density of the round to modify that caliber's Penetration value. I would use the following modifiers based on Sectional Density:
SD of less than 1 = Increase PEN by 1 level (3 becomes 4).
SD of 1 to 1.9 = No increase in PEN.
SD of 2 to 3 = Decrease of 1 in PEN (3 becomes 2).
SD of more than 3 = Decrease of 2 in PEN (3 becomes 1).
I also use a round's Velocity to determine Penetration. I have modified my original chart to take into account real world ballistics AND to better "mesh" with Twilight's integrated Penetration-Damage-Armor Value system.
My Penetration Ratings have changed to the following:
5400fps or more = 1/4 PEN
4000fps to 5400fps = 1/2 PEN
2800fps to 4000fps = 1 PEN
1800fps to 2800fps = 2 PEN
1000fps to 1800fps = 3 PEN
1000fps or less = 4 PEN
I "overlap" my velocity numbers to give the developer/GM the flexibility to round up or down based on a round's real world performance characteristics.
I also allow for modification of PEN for certain designs of ammo. If a round is known for good penetration BUT has a lower Sectional Density (like the various PDW rounds such as .30 Carbine or the 5.7mm X 28mm), you can "swap" Damage for Penetration. The best formula I have found is to
Multiply a round's Velocity by X1.5 to find its PEN Number. Nothing is free, though. If this modification to PEN is made, the round's Damage must be recalculated as well.
Multiply the Energy of that round by X0.75 to find the new (reduced) DAM of that round at a given range. This is the "tradeoff" for increased PEN. For example:
The 7.62 Tokarev round is well known for its penetration, being able to punch through EVERY cold war helmet and easily penetrating NIJ Level 2A soft armor in its military steel-cored loading. The 90grn steel cored military round averages 1460fps and achieves 426ft/lbs of muzzle energy. Using the formulas above, the 7.62's PEN improves to 2 (from 3) when you multiply 1460fps by X1.5 (2190fps). Its Damage drops from 3d6 (for an energy from 401ft/lbs to 600ft/lbs) to 2D6 (for an energy from 250ft/lbs to 400ft/lbs) when its Energy of 426ft/lbs is multiplied by X0.75 for 319ft/lbs of energy. This gives it the ability to penetrate NIJ Level 2/2A armor (1/2 AV) while still being stopped by NIJ Level 3A armor (AV1) just like it is in real life.
These newer numbers are based on about 3 months of in-game play and seem to be working ok now.
I highly recommend several Youtubers for those interested in Armor Testing and Materials Penetration testing. Check out:
The Military Arms Channel: Tim was the first person to test Dyneema NIJ Level 3 (rifle) armor and has several interesting videos.
The Wound Channel: He was one of the first YouTubers to discover that 3000fps is the threshold for penetrating an NIJ Level 3 (rifle) plate. He also demonstrates that M193 Ball actually penetrates BETTER than the SS109/M855 round. I HIGHLY RECOMMEND HIM.
The Chopping Block: Much like the Wound Channel, He does a lot of armor/penetration testing.
MikeB: He has shot virtually EVERY helmet made in the 20th Century. Go here to see the 7.62T punch through EVERYTHING but the PASGT helmet.
ShootingTheBull.410: This man has test HUNDREDS of rounds in ballistic gel. He is a true authority on "stopping power" as the FBI tests for it.
These are just a few of the better YouTubers out there. There are others such as PocketGunsandGear, TN9Outdoors, ScubaOz, Taofledermouse, and DemolitionRanch. I hope you can use some of this to fix your issues.
Swag.