Writing an Action Scene

I'm in the middle of a revision of The Sandfruit People, and I need to add a very pivotal scene that's very action-intensive.

That's right, I said it's a pivotal scene. Somehow, I had managed to write the entire book and leave out a very important part. Credit goes to M. Joseph Murphy for catching this. This is why a book needs to go through several hands before it hits the shelves.

Personally, I hate sloppy action scenes. The page may be full of adrenalin, the pacing may be perfect, and the hero may come out a larger-than-life winner, but it's not really clear what happened (or worse, if what happened is impossible), the readers are going to be left smirking and rolling their eyes.

The scene I need to write for Sandfruit describes a very specific kind of weapon attack. There were three requirements already present in the story:

1. The target is pretty tough and can't be taken out by a rifle.
2. There can't be a lot of damage from the attack, so it can't be done with a bomb.
3. The attacker is a US soldier who just happened to be there with the right kind of weapon.

So I did a little research and decided the only weapon that fits those restrictions is the FGM-148, otherwise known as the Javelin.

But that's just the beginning. Now I need to learn all about how it's carried, how it's fired, how big a backblast it has, how big each of it's two explosions are when it hits, and probably other details as well.