as jhalcott stated, the bullet will likely pass through the deer.
My own feeling is that we, the users of cast bullets, have gone overboard on bullet hardness. At the velocities you're using there is simply no need for an alloy harder then 1:20 (tin to lead). And bullets of this (relatively modest) hardness will normally expand much better on medium game like deer, as well as produce some secondary fragments within the would channel complex that contribute to a quick kill.
Despite the ballyhoo of the ads, the plain fact is that in most arms well designed bullets of medium hardness will produce less leading related problems up to 1200 fps, and with selected loads up to 1400 fps, than will harder bullets.
Bob