In my 30HBR (a 30x47 with a sharper shoulder) I use a BIB 136gr, 10ogive bullet in front of 42.8gr of Vit 135 powder. The Berger 135gr flat base bullet is a great second choice in my barrel. I use 300 Savage Rem brass with a CCI BR2 primer. My barrel is a Shilen 1in15 twist. It loves this load, but...yours may not. Start about 10 percent below this load and start from there. If you subscribe to "Precision Shooting" magazine the loads of the top winners are listed and there are plenty listed for 30x47's. Per experiment I don't think the primer choice makes much difference. I've used Fed match primers, Rem 9 1/2's, Wolf primers, and Win large rifle primers with good results. But...I love the little "B" letter on the CCI primer which tells me instantly what primer is in that case. Of course now that I use CCI's exclusively that no longer applies.
However, with your slow twist barrel, a lighter bullet and a different powder may be called for. Try 112gr or 118 gr BIB's, Cheek, or Bergers. Also a faster powder like Vit 133 may be called for. But...a hotter powder may not fill your case before giving pressure indications. The lighter bullets and hotter powders are more effective in the 30BR or 30ppc calibers.
I'm sure other will pipe in here to give some excellent advise as well.
Good luck...virg