I friend asked me a question this past weekend and it really stumped me. Apparently he shot three or four 7mm Ultra Mag rounds down a gun chambered in 300 Ultra Mag. Might have been Weatherby but I'm pretty sure he said Ultra mag. He can no longer get this gun to group like it did before. It has never been viewed with a bore scope. What kind of damage if any can you do to the gooves and lands by doing this. I would think the 7mm bullet would bounce in the bore, scuffing the rifiling. What say ye?