I have an old Remington 760 in 300 Savage caliber that is no longer grouping it's shots like it use too. I'm wondering if the barrel is in need of replacement or if something else is going on. The barrel is shiny and is not pitted. I have always shot handloads and in the past, thru trial and error, have been able to work up differant loads until I have been happy with the results. I've hunted with this gun for 25 years would really like to continue using it. I would appreciate your expert advice.