Re: Different types of ojives, how are they relavant?
Secant ogive bullets become longer for the weight, making them more difficult to staballize than a tangent ogive of the same weight. Secants tend to benefit more from controlling freebore than tangents. Many people find slightly better accuracy with a secant ogive bullet, although certainly not always the case.
The curve of a bullet is a section of a circle, most commonly in a tangent ogive that circle is 6 times the diameter of the bullet. The curve joins the widest part of the bullet without intersecting it, it's tangent to the curve. If you continued to draw the curve, the line that makes up the side of the bullet would touch it at one point.
On secant ogive bullets, the curve inersects the side of the bullet, so you end up with a cusp at the ogive. If you continue to draw the curve out, the line with intersect at two points. I think the curve is more commonly 9-10 time the diameter of the bullet with these.
Sierra match kings are tangent ogive, as are most bullets. Secants are made by berger and lapua, are the first two that come to my head.