a deeper extent than other lands this will result in the longitudinal axis of the bullet being off center from longitudinal axis 22 of bore 14 since the longitudinal axis of the bullet passes through the center of gravity of the bullet the center of gravity of the bullet will travel in a helical spiral pattern about the longitudinal axis of the bore such helical spiral travel creates a lateral velocity component to the forward motion of the bullet upon discharge of the bullet from muzzle 80 the lateral component of force will act upon the bullet and affect its trajectory as particularly shown in fig4 bullet 16 is not laterally expanded sufficiently to ensure contact by the surface of the bullet with each of bottom surfaces 20 of grooves 18 the amount of space therebetween will vary for each bullet and as between bullets discharged through the barrel transition section 60 defines a section of increasing land diameter and therefore a reduction in radial distance between bottom surface 20 of each groove 18 and land surface 32 of each land 30 the ratio of land diameter radius to groove diameter radius will increase such reduced difference urges bullet 16 to expand radially until each of grooves 20 is essentially filled and the bullet bears uniformly against each of bottom surfaces 20 see fig5 the resulting complete or essentially complete contact by the bullet with each of bottom surfaces 20 ensures that the longitudinal axis of the bullet and.