The larger diameter on the muzzle end is designed to give a slight choke which helps accuracy. If as you push a tight, lubed patch down the bore from the chamber end it gets tighter at the larger diameter near the end of the barrel it is correct. If the patch gets loose any where down the bore, you have a ringed bore and it isn't likely to shoot well. My rifle as mentioned has a 1/2" long loose spot where the larger diameter portion begins and won't shoot less than 1 1/4" at 50yds.
