It's very important if accuracy is your goal. The base of the bullet steers the bullet, not the nose. If the base isn't as nearly perfect as you can get it accuracy will suffer. If one side of the base has incomplete fill out the bullet cannot spin on center because it's off balance. A defected bullet with the defect covered by either lube or a gas check is still a defected bullet, you just no longer can see the defect but Mr target can and the faster the velocity and longer the range the more effect there is.
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