I've got a Win 70 featherweight in 280 that is the same way. Would not start grouping until 10 rds had already been sent down the tube. So, I scrubbed it all down and applied the Dynatek ultra bore coat, shot till it started grouping again and haven't cleaned it since. It'll put Berger VLD's into under 1/2" groups. I'll probably never clean that barrel again.

"Freedom is never more than one generation away from extinction. We didn't pass it to our children in the bloodstream. It must be fought for, protected, and handed on for them to do the same." - Ronald Reagan