This is a very general question...I'm assuming you are going to use the gun for hunting deer...
I have used a .243 since 1980 and have used most of the factory loadings...I have seen the
best results on deer in the 100 grain loadings with the Hornadys, the Federal Premium Sierra
GameKing SPBT, and Nosler Partition and the Remington CoreLokts...I have killed 8-10 deer with
all of these....That being said, I have gone back to the CoreLokts because my Ruger just loves
them...I have killed about 80 deer with that bullet, but I would be comfortable with any of the
above...
I have also had good luck with the Federal Premium 85gr Sierra HPBT, killed at least 30 deer with
this one, it outshines the others once you move past 200 yards...If I reloaded that would be my
bullet especially when hunting over fields.