Lloyd, the 243 kills deer best with 100 grain slugs. When I had my 243 the best load I found was with 40 grains of IMR4350 and Rem. 100 grain C/L bullet. I used Win brass and Win standard large rifle primers and seated them really close to the lands. My rifle didn't like boat-tail bullets at all. All three of my kids started out with the 243 but have since moved up to 30 calibers, even my daughter now has my 30/06 that used to be my deer magic.