A 155gr bullet is fine for 500 yards. For that matter, so is a 135gr or a 210gr. What really matters is the velocity that you can push them at.
You might try the JBM ballistics calculator with your specific bullet and velocity to understand a bit more about how well your cartridge/rifle will operate out to 500 yards.
JBM Ballistics Calculator
"Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety." Benjamin Franklin, 1755
Last edited by mattmcg; 05-05-2011 at 3:33 PM..