Wow. Another great script Grendel! I have a few comments though:
The tracers don't really look right, IMO. They look more like fireballs (maybe cause they are fire particles lol). I think you should use the cl_fired particle instead of cl_fire; both of them glow in the dark, but cl_fired doesn't have the fire-color like the other one. I'm not sure the color of real flak, which is something to look into; but I know it should have a constant color all the way through, not red here, yellow there, etc.
You should also make the particles smaller. And to make them look more like a "line" (a point of light travelling at high speed looks like a line, not a point), you could drop maybe 3-5 of them with very little delay between, giving them all the same velocity. Thus you would have a line of particles travelling through the air; find the right balance between size of particles, delay between them, and number of particles per "shot", and it should end up looking much better.
Now if only there was a way that sum1 could make an addon that, when you shoot the aaa cannon after a set period of time the bullet would blow up like a real flak
Check out the Wargames mod; it has exactly what you are looking for (from what I've read). It wouldn't be too hard to script either; just use a fired EH to catch fired bullets, and run a simple script on each one that waits a second or so, then camcreates in some explosives at the bullets location.
Say, Grendel... little off topic, but I've got a question about your ACH-130 script. I
really want to use it in a mission, but I want to have the real thing; meaning, the ac-130 plane, not helo. I tried using the script with a c-130 addon (Cpt. Moores I think?), but it didn't work quite right. The plane would make a much bigger loop than the helo (as expected), but when it fired, it would aim too low, so the rounds would fall way short; it kinda looked like it aimed in the same place the helo would aim, only now it had a much larger radius around the target. Any chance you could modify the script so it is useable with a C130 addon? If so, I would even recommend getting together with the author of a c-130, and integrating your scripts into the addon for easy AC-130s, and more publicity for yourself.
Hey, have you ever thought about joining the ECP? We could use more great scripting talent like you.