you need to break in the new bolts/receivers but that is about it.
The new ones are plenty accurate as well, so don't sweat it. Just try about 30 diff types of ammo, and you will find a few that will ber very accurate. Try Out CCI's, Aguilas, american eagle red box. Also try winny experts, bulk box, but most bulk ammo will be crap. feddy's bulk should be the red box American Eagles. but if you find something else bulk feddy , give them a try.
Also remington/eley orange, or yellow box, then golden eagles, in the blue/black, or brown/black boxes. The most expensive of this ammo will be the rem/eley orange and yellow boxes, all the rest should be less than 3.00 per box.
Oh yeah, try wolf ammo as well.