For the handloader, the 7-30 Waters or 30-30 AI are among the best deer cartridges around for the Contender out to about 250 yards. The good ole 30-30 will do well, as well as the 6.8 SPC, 300 BLK (300 whisper/screamer/etc), and 35 Remington for those who shoot factory. There are also the various JDJ chamberings if you want to go that route. What twist is your 223 barrel?

Rod, too.

Short cuts often lead to long recoveries.