Here are just a couple photos of Black Ops Models' GAU-19:
There are no assembly instructions. You get a length of tubing for the 3 barrels, the flash hider/barrel ends, 2 parts for the gun chamber/motor, a section of flexible ammo chute and 2 parts for mounting it to a helo pylon of your choice (?). All the parts were well cast with no apparent bubbles and very little flash. The pour stubs are well located to be easily removed without damage to the parts.
As previously mentioned, it would be nice to have a pintle mount option, so I'll be scratching that when I decide what project to use this on.