I have a Rem 600 308, 18" barrel. Had the same problem with expansion. 150's to 180's I was either dis-satisfied with expansion or velocity. Wound up trying a 125gr BT/AB with Varget, against what many said was too light. BINGO !!!! Just don't try to bust through a shoulder blade and it will flat out Hammer deer.

"Be polite, be professional, and have a plan to kill everyone you meet." Gen. James Mathis, USMC