Third Person Muzzle Flash

Thanks for all the suggestions. In the end, I decided to go with something quite similar to what Vorderman suggested, except that I've actually used half a sphere for the cross section instead of a third plane.

It was a little tricky to get them rendering perfectly, as the crossed alpha-blending planes were producing a few artifacts, but by disabling depth-writing and z-sorting correctly, it seems to be working quite nicely now.

Thanks again.