Ogive Measurements

[smoky]

I am trying to accurately measure my chamber length from case head to ogive.  I have split the neck on a resized case in order to "long seat" a bullet, place it in the chamber, close the bolt, thus allowing the compression from the ogive hitting the lands.  I then measure this using my ogive tool attached to the calipers.

My question is this. When I do this proceedure using two different bullets, say a ballistic tip and a flat based spitzer, I get two different readings of case head to ogive.

Now I realize that different bullets have different ogives, but if I'm using the chamber and lands to compress to fit the case, shouldn't the case head to ogive length be the same regardless of bullet used?

Smoky

[ricciardelli]

Some bullets have a secant ogive, and others have tangent ogive.

[Iowegan]

smoky, Not at all. Each different type bullet will seat to a different depth. The ogive is the place on the bullet where it first measures full diameter. A bullet with a long point will have the ogive set back pretty far. A round nose bullet will have to ogive set near the front.  Check out this web site for tools that measure what you are talking about.  http://www.cactustactical.com/reloading.html

You can make an ogive checker pretty easy. Just take a sized brass and insert a bullet into the case nose first. The bullet will stop just short of the ogive.

The definition of ogive varies. Some define it as the curved portion of the bullet nose while others say it's the point on the nose where the bullet first measures full diameter.  The latter is much more definitive.

[Duffy]

Also if your tool is a bit different sized than your bbl thoat. In my bullberry bbl all bullets seat the same but in the standard bbls they vary quite a bit.