Thanks guys for all the advice. I am planning to have a barrel made so I will not be useing a ready made barrel. Tom, I have had B Hoyt rebore and make me barrels and he does do excellent work. I like your idea of a 66 twist and i dont think that is too fast for a ball or a slug. TLRF below is the slug I have been looking at it weighs 425 grains in WW lead. Keep in mind that these molds are custom made and can be modified to any configuration I desire. I can even design my own mold. I have used the green hill formula many times and it always come out in the 90's twist range which would take a too much powder to stabilize a basically "square" slug. I do want to keep this in the managable 70 grain powder range. I am only wanting 1200 give or take velocity at shorter ranges much like the old paradox guns, what twist did they use? Not a whole lot of info on them.,,,Ed

http://accuratemolds.com/bullet_detail.php?bullet=62-425S