With a 12" twist you can use up to 200 grain bullets, but to keep velocity up the 150/155gr is what most shooters use, I have had very good accuracy with all the major bullet manufacturers 150gr bullets just try as many as you can either afford or lay your hands on, I don't know what the price difference between the makes are over there but down here Speer are the cheapest Sierra, Hornady, Nosler are about the same for their standard bullets, Berger Barnes and the fancy
stuff by the the others are as much as twice the price, Speer Sierra and Hornady all make 150gr spizter boat tails if you want slippery bullets for long-range shots all will kill any Deer you are likely to run into at sensible distances, with careful load development you should be able to get .5 m.o.a accuracy if your rifle is capable, match grade bullets won't get you any better unless you have a purpose built target rifle.
Robert.