The 600 bullet profile allows for better straight line penetration than the RN of the .577-750gr. The 577/750 Woodleigh is too pointed for deep straight line penetration. Look at the bullet penetration tests listed over at Accurate Reloading that have been done by Michael458. The 900gr Woodleigh solid was tested at 600NE velocities and it was straight for 50". Given the choice of a vintage .577NE or .600NE I would definately choose the big 6. I am confident that most would agree with that choice.

BR