I bought two for a display i did in 2002 for my family, the burst from them was quite large. 12g!!! thats way too much, maybe it was dirty flash? I got some zink 4oz rockets too and they were very nice, shimmering saphire was beautiful!
The 12g of flash wasn't actualy in the shell, it was placed between the opening at the top of the motor and the shell. Heres a photo to illustrate: -
http://i11.photobuck...22/505c3d38.jpg
It must be there to help break open the thick outer cardboard tube/plastic nosecone facade as the shell bursts to reduce interference. Also it might be to guarantee ignition of the passfire fuse into the shell, but 12g seems a bit excessive for that purpose!
