Deep recessed crown

[Shawnba67]

Some years ago, I had a good friend that was involved with building Olympic rifles. He and Bill Davis did some extensive work on taking pictures of bullets as they exited the barrel in as far as how turbulence at the muzzle had an effect on the base of the bullet. They also played with taking pictures in how far a bullet would yaw, in relation to it's design.

If you want a clue, look at a Rocket platform, base of rocket launchers, and how escaping gases are directed away from a rocket. This is NOT conventional thinking in how muzzles are crowned today.

This is surprisingly hard to google! It may be I dont know when Ive seen it. Can you link a pic? Or describe the shape your talking about? Thank you