I shoot 168's in a 14 twist for my 300m load. (scenars) In the 12 twist, I would expect 185's to be OK depending upon their length. I know 190 Matchkings are OK.
Primers:
I use mostly CCI 200s. I have used BR2's but, quite honestly, have not seen much difference. I used some Dominion primers (Russian) and they worked very well, I'm afraid of Winchesters since some have cups which fail. Try different primers and see what shoots best for you. I have found that rifles often prefer a certain primer. GD
