if ya have a boss, use it...boss is what re-loaders do by time exhausting measurements and hours and hours of pain stakin work, just to get the vibration of the barrel to be in tune...if your accuracy is gone, look on browning and see what they recommend you set your boss to start the tuning process with a particular round....i'd imagine if ya have a boss, then ya know what i mean. if ya use it properly, and take the time to figure it out, you can change bullets with 3 practice shots and be inside 1" groups after that.