I read a good article on '06 somehwere (Chuck Hawks ?) that the first mil version was 172gr, and it was preferred by Vietnam era snipers to the later mfgr 150gr ball ammo.

As for bullet weight choice....try a few and shoot what your gun likes best. I'm not the first to offer up that advice, just a proponent of the philosophy.

If you want really good info on center fire accuracy and bullet choice compared to twist rates, talk to any high-power rifle nuts that shoot at Creedmore and/or Palma type matches.

Me...my '06 likes 180gr Wolf Gold. I've got some b-tip Hornady's that shoot good on paper, but have yet to meet some meat.