Current Version:
Beta 1

Description:
What does this mod do?

This is a crude attempt at making the physics of bullets closer to the real world. As we all know, Fallout 3/Gamebryo is a terrible platform for emulating real world ballistics and physics in general, but this can help a little.

The main thing this mod does is try to copy the velocities of the real world bullets represented by the bullets in xCALIBR, and also the vanilla bullet projectiles. The data I got is gathered from various internet sources, featuring the average velocities these bullets travel at muzzle when fired from various guns. I also tried to pick a middle ground between the various weights and kinds of the same round (full-metal jacket, jacketed hollowpoint, etc.). The result is an abbreviation of all of that data. I used the formula with the assumption that 10 "Speed" = 1 foot per second. This may be inaccurate, but from some testing, it seems that firing the weapons in-game brings somewhat similar results to what you might expect when you fire the same cartridge from the same gun in real life.

I also applied a very subtle bullet drop element. It's so subtle that you might not notice it for most guns, but it definitely works for higher ranges, and also allows you to aim more accurately when you get used to it (with 100 Small Guns skill, I'm able to hit a headshot accurately with my main sniper rifles at a range of about 130m, according to this rangefinder mod). I mainly did this to counter how bullets seem to rise at a range because of the scopes for most guns being zeroed for ranges below 75m.

I removed a lot of the tracers (but not all). Sniper rifles from mods might use the tracer version of the projectile, especially if they share an ammunition type with a machinegun, which needs tracers (the 7.62x51mm, 7.62x54mmR and 5.56x45mm NATO rounds are typical examples). I have not touched any weapons with my mod, and it's generally not an issue. I left tracers in many pistol rounds, because it's a little harder to aim in third person at close range. It's nice to see where the bullets are going so you can easily adjust.

Maximum ranges are also adjusted for all projectiles. You should be able to see some impact effect if you fire into a hill some 500m away (if you have your LOD/distance settings up that high), and you won't be able to see the same effect if you fired a shotgun or a pistol into that same hill.

Lastly, I also adjusted the impact force. I actually did this part just for fun, but I based it on the formula of 1 impact force per 10 ft-lbf. If you fire a high-powered gun like a Barrett M105 into a tin can, for example, it should cause the tin can to fly up into the air. It's not really realistic but it sure is fun to watch. :)


Requirements:
eXcalibr

Installation:
1. Extract the contents of the archive using 7zip into your game's Data folder.

2. Activate the mod via the FO3 Game Launcher, or your favourite mod manager.

Optional: If you're using Wrye Flash, you can merge this into the Bashed Patch, to reduce the number of active mods.


Incompatibilities:
Any mod that edits the projectiles (PROJ) of the ammunition added by CALIBR.


Load Order:
This can load anywhere in your load order, since the only mods it depends on are master files. If you have other mods that edit projectiles, loading this after those will override their changes. Loading this before those will prevent my changes from occurring as well.


FAQ:
Q: How realistic is this?
A: Fallout 3/Gamebryo doesn't give us accurate ballistics or physics in general. In real life, a rifled bullet will travel in a fairly straight line until it starts to lose velocity and gravity starts to take effect. The distance at which this starts to happen is more dependent on the rifle it is fired from rather than the cartridge itself. In the Gamebryo engine, the projectile travels at a consistent velocity until the projectile's maximum range, at which point the projectile just gets disabled. The game's version of "gravity" is also constantly affecting the bullet. The velocity of the projectile will affect how much the "gravity" affects it. So for slower projectiles, like shotgun pellets, which typically travel at below 800 FPS (feet per second), gravity will have more of an effect than a 5.56x45mm NATO round, which typically travels at about 2,900 FPS when fired from an AR-15. This is about as realistic a compromise as we can get.

The only other way to make sure that each gun fires more accurately represented projectiles is to make a projectile type for every weapon. While that's possible, it's too much work for such small benefit. This is the best we could do without wasting too much time.


Q: I read somewhere that "bullet drop" doesn't actually work. How did you get it to work?
A: Actually "bullet drop" works just fine in FO3, but is not introduced by default in vanilla and by most mods because it's normally unnecessary. FO3 was designed for really short-ranged encounters, where bullet drop wouldn't be noticeable at all. However, with a lot of weapon mods being designed for snipers, and modern technology allowing us to see great distances (my game seems to load and display enemies up to 200m away or more), I thought that bullet drop might be an interesting thing to see.

The game's "gravity" system is typically designed for thrown/lobbed projectiles like grenades. But it also works for "missile" type projectiles, which is how we classify bullets in game terms. If you are skeptical, you can try messing with it in the GECK. Create a projectile that goes at 3000 "Speed", put a tracer on it so you can track its movement, then add a "Gravity" value. Anything more than 0 at 3000 Speed is instantly noticeable. In fact, if you set it to 0.50 gravity, the bullet will effectively land on the ground maybe some 10 meters away if you shoot straight.

The simplest example of this in vanilla is the Rock-It Launcher projectiles. The Rock-It Launcher fires at 3000 "Speed" and has a "Gravity" of 0.35. Watch how the bullet falls when you fire a tin can or a teddy bear at a distance.


Q: Why did you use eXcalibr instead of just plain CALIBR? Will this work with just regular CALIBR?
A: I chose eXcalibr because I like the graphical changes it makes, but I liked my tweaks to the "physics" aspect a bit more. I originally didn't want to release this mod to the public, so I didn't really think about making it compatible with plain old CALIBR, because I'm using eXcalibr anyway. This mod might work with plain CALIBR, if you edit the required masters somehow, as CALIBR by itself doesn't edit projectiles. However, this is untested. Try it at your own risk.


Q: Any plans to do a mod like this for Fallout: New Vegas or <insert mod name here>?
A: Maybe.

As for other mods, I might be able to, however I think it's smarter to just make the other mod compatible with eXcalibr via a patch. I use this with FWE, EVE and Apocalypse Armory, which are all compatible with eXcalibr and my mod via a patch.


Credits and Permissions:
This is a mod of the original eXcalibr mod by EARACHE42, which grants free permission for modification without repackaging its original contents.

As such, I also grant the same permission to freely modify my mod as you see fit, though I would appreciate if you gave feedback here instead so we can further improve this mod, and everybody can benefit from it.