I've been useing redding competition dies for two different calibers and Iam getting a ring around the front of the bullet below the tip after I seat them.I've tried using a bigger bushing when I neck-size but that will not size tight enough to hold the bullet in place.Why is this occuring?How can I avoid it?

Because the profile of the seating stem does not match the profile of the bullet...

have a machinist cut a convex rad on the id of the bullet seater stem...make sure he does it concentrically...that way no matter what ogive you use it will hit the bullet on the convex radius, and not the sharp edge of the ID it is now hitting on. Or put the seating stem in a hand drill and turn it on and use some 280-320 sand paper and get a nice radius at the end of the id, so you will get a much less noticable mark....Bob