Stan,
You need to get this book.

http://www.anglebooks.com/climbing-the-north-face-of-the-410-by-tim-woodhouse.html

The author is a .410 fanatic from England and he's done all kinds of work on ballistics/barrel geometry. It's not very polished, but it is interesting. I'm on the verge of selling everything .410 that I have including reloaders, components, ammo and guns. I already shoot 12, 16, 20 & 28 gauge and the little gun just doesn't entertain me enough. Maybe I should give it another chance.
Jeff

"We are men of action. Lies do not become us."
Wesley