CVA Scout Barrel ?

My CVA Scout loads my resized 250 gr plastic tip bullets or XTP's with a firm thumb press till flush with the muzzle. They push down with same pressure till about 12 inches from the breech and then require a two-handed firm push to seat on powder load.  After firing successive rounds (10), the bore gets tighter and requires a starter, but the breech end becomes more difficult and needs palm tapping to seat.  Would there be a loading ease and accuracy benefit to me lead lapping the breech? Or sizing looser at bore so bullet seats easier at breech? I am satisfied with the accuracy as it is.  I am sure the gun would improve on that end in more competent hands or better bullets.  It is a 25 in. stainless gun with no brake.