I wouldn't give up on the Browning...After you have checked all the scope mount screws and the barrel to action screws, try some of the Federal Premium 140 gr Accubonds....

My cousin had me sight in his Browning last year, I think it is a Gold Hunter, thing was beautiful, had a octagon barrel...With the Accubonds, I put 3 shots inside a quarter at 100, good shooting gun...