[Nightcrawler]

Does anybody know what the projectile weight (typical) and muzzle velocity (also typical) of the US M61A1 "Vulcan" 20mm cannon is? What about the 30mm projectile from the GAU-8(A) "Avenger" cannon that the A-10 uses?

[Mike Irwin]

Well, if the 20mm system anything like the Phalanx system used on US Navy Ships, here's some statistucs on it...

Scroll down to the projectile specifics...

http://www.warships1.com/Weapons/WNUS_Phalanx.htm

[Nightcrawler]

Hmm..actually, I don't know. It would make sense that the military would use standardized 20mm ammo (the modern, electrically primed stuff), but then again, "making sense" has never been high on the Defense Department's list of priorities.

[Navy joe]

Well the CIWS is also built around the M61A1 cannon but different ammo comes in to play. DU for the CIWS and HE, Training(TP), and other stuff I'm sure for the airborne guns.

Here's some info on the gun, nice pic. http://pma265.navair.navy.mil/Public%20Affairs/stores/m61a1/m61a1.html

http://www.combatsimulations.com/cannon.wav Kinda what the cyclic rate sounds like, doesn't do justice to the noise level. Sounds like the biggest unmuffled chainsaw you could find plugged into the biggest amp you could find.

Here's a page on the M50 ammo series, http://www.atk.com/productsPrecision/descriptions/products/20mm-overview.htm Another site lists projectile weight as 98grams although I'm sure there are several different weights.

[Nightcrawler]

I've heard both the Vulcan and Avenger cannons fire. The Air Force is always zooming around over us at Annual Training, firing their guns at the bomb range. Sounds like a BVVVVVVVPTT sound, very loud. The 30mm is deeper than the 20mm.

[p35]

Just wondering- why DU in the CIWS? Missiles are generally pretty lightly built, not armored, I thought. Wouldn't an explosive round be more effective?

[Elmer Snerd]

Possibly because DU is pyrophoric(the bits that break off on impact ignite).
http://www.heritage.org/Research/NationalSecurity/EM721.cfm

[Daniel Watters]

You need to remember that many of the Russian anti-ship missiles have been the size of a small jet fighter. The fear is that a missile's airframe and fuel tanks may still hit your ship in a ballistic arc even if you have succeeded in knocking off a wing, setting it on fire, and/or disabling the guidance package. As a result, the goal is to punch through the guidance package and hopefully detonate the warhead in mid-air.

The basic scenario dates back to the hard lessons learned from the Kamikaze attacks of WW2.

[Echo23TC]

Nightcrawler, the 25mm cannon on a Bradley shoots the following:

SABOT projectile weight 96 grams @ 1385 m/s
HEAT projectile weight 185 grams @ 1100 m/s

That data is for service rounds, not practice.

Not quite what you were looking for, but the best I could come up with.:)