[justashooter]

the 148 wadcutter with hollow base is an industry standard that is designed to be seated flush with case mouth. it has a standard legnth and dimensional form. the 158 SWC is less rigid as a generic shape, but pretty reliable in terms of lenght from front to rear of bore diameter section. this allows thousands of casters to make similar bullets that occupy the same amount of case volume by type. this allows reloading manuals to offer loading suggestions with reasonable expectation of consistency regardless of the exact bullet shape, as long as it's in the generic profile.

your gun will eat either type of bullet equally well. you could clamp it to a shooting bench machine rest and shoot for accuracy and see no difference related to bullet weight. you might see the 148 WC as more accurate at <25M due to consistency in pressure curve during burning yada yada, but the SWC will be more accurate >25 M due to aerodynamic shape.

load your 148 HBWC with the hollow base into the case and about 3 grains bulleseye or similar fast burning powder to get 700 FPS give or take 50 fps and you will get accuracy. load SWC with unique or similar to about 850FPS and you will get accuracy.