I went to the range yesterday and brought my 270 with pac-nor barrel. The barrel has been broken in properly and has about 50 rounds through it. I noticed at the range that after cleaning the copper out, my accuracy is not as good for a few shots. After about three shots the group shrinks up to about 3/4" (100 yards). Right after cleaning, the groups are about 1.5". How long can i go without removing fouling?