Well now i have got some new expirience.
I used to clean this rifle like all my others, including my comp rifles in 6,5 swede, which i shoot 4-5000 shots with a year.
Well it seems it hasn`t been good enough. It has now gotten what i call a judgementdaycleaning. About 5 days soaked with different chemicals, brushed like f... each day and polished 4 times with gold medallion.
Today i shot 35 shots with no problems. Same brass, same load, same bullet, with silencer.
5x5 shots at 430 meters - 480 yards.
Todays best group, and the worst.. Looks like that Krieger barrel is ready for hunting
Had to be it.
Glad you have worked it out