SpudFiles

Well, gasoline is carcinogenic also,,, Anyway, about assembling, how to do that?

Uh, most things I've seen say about equal parts polystyrene and gas, though I'm not sure if they mean volume, or weight. They say it can take a while for the stuff to dissolve. I'd say just ad bit by bit until you get a consistency you like, then make more.

Nonono, not the napalm, I've got that more or less perfected, I'm talking about the firework shell.

I thought you said you knew how to take apart the shell and do it that way. I think I know what might do you good though. IF you can take apart the shell and put it back together SAFELY, just take some of the napalm and put a very small amount in some cellophane and put it in with the powder load. That may work.

I know how to assemble them, I was just wondering if you thought it would hold together if I used just masking tape. Ya, but then I won't get a globe of fire, just little fireballs everywhere. I wanted it to create a literal ball. How could I do that, but seal it so it doesn't spoil the powder or dry up? You see, in my original concept, the napalm is smeared on the inside of the shell, so it makes a ball shape. But, like you said, it could mess up the powder, and it would prob dry up if I just put it in straight.

Edit: However, I may have to settle with little fireballs......

Polyethylene or polypropylene is resistant to gasoline, and can be used as a container. I'd rather use something more volatile though, such as pure gasoline, ethanol or even acetone. That would spread into a fine mist and ignite when the shell explodes, producing a fireball.
You'll want the fuel to burn with only regular air, as a fuel rich flame will be more visible. You'll hve trouble getting a solid oxidizer to work with a liquid fuel in any case, since its decomposition temperature is higher that the boiling point of the fuel it won't activate until it has boiled off (and probably not at all).

Take a ping pong ball and fill it with Gasoline and mothballs(mix for blowing cars up in movies) or your napalm.

You guys really need an IM
For a fireball I would use a plastic container and pressurized propane with a small charge for ignition. In theory, a 1liter bottle could hold liquid propane, but if the plastic becomes brittle from the cold it could rupture before you intend it to.

If you are increasing the mass of the ammo then you'll need to increase the strength of the launch tube.

Bad day&tm; if the launch tube fails because of the higher pressure needed to get the heavier projectile out of the tube. You really don't want to be around when a star-shell type tube fired firework explodes near the ground.

Overall, this is really a dumb / stupid / dangerous / irresponsible / illegal / 13-year oldish thing to try to do.

Haha, I've seen them do that. I really thought this kid was gonna die. The thing fired but the tube blew and teh shell was laying on the ground, the kid just stared at it for the longest time and then dove away. But really, the amount of mass we're talking about adding here is inconsequential.

strike any where matches

Erm, I don't want to make bombs, as I was saying before.
And, I matchheads were already suggested by paaian.

EDIT: But, yeah, I see what you are getting at, matchheads are pretty easy to catch on fire.

Any more suggestions?