Thanks a million Ghost Snake, and I'll be your friend for life if you share the location of that ballistics calculator, I like the features it has! much fancier than the junk I've been using. (unless you took a screenshot of a purchased program). I'll give this address I've got on energy conversions, in exchange:
http://www.ajdesigner.com/phpenergyk...ation_mass.php
And I'd really really like to see the work on the BC calculation, what shape is it based on, etc?
"Ke=5.7joule, v=152meter/second, mass (m)=7.6146505031079 grain; 0.49342105263158gram"
I'd agree that safety is the top concern, and that velocity is limited, as is energy. But I believe there is some wiggle room that satisfies ballistics, safety and legality. Just need to find it!
For instance, retained velocity is based on the ballistic coefficient. It's possible you can get better retained velocity by increasing mass and reducing velocity proportionally. On top of that, there's form factor, the air resistance of the shape.
Also thank-you Myoga, I did understand better when you explained it.