The .243 can use all the help it can get for shooting deer, in the form of a premium bullet. Use the Nosler 95 or 100-grain Partitions if you can find a factory load that uses them. At the minimum, you should use the remington 100-greain Corelokts. A 70 grain bullet is much too light and frangible for shooting deer. You'd run the risk of blowing big shallow wounds in them, after which they'd run off to die unrecovered.