The difference between the 500 and the 505 is bore size. The 505 Gibbs is a true .505" grove to grove, and takes byullets of that size. Whereas the 500 is actually sized .510" grove to grove, and takes bullets of that size!

But the Jeffery and the Gibbs should be perfect for all dangerious game anywhere in the world!

I have only shot the Gibbs so I cannot comment on any of the others! The Gibbs is awsome!!