ruger no. 1
It sure sounds as though you've got a classic example of barrel and stock contact when it heats up. Try running a dollar bill between the barrel and stock to check for tight spots that could cause the stringing.
Have you checked the mounting screws? You might want to call/write Sturm Ruger about their recommended procedure is for tightening the action to the stock.
savageT........Have you hugged a '99 lately?
Of all the things I've lost in my life, I miss my mind the most.