ogive oal question

[philip brousseau]

if you sort your bullets base to bore diameter and then seat them will the bore diameter of the bullets all be the same distance from the lands. if we took the measurement from the bullets in the seater cone to the bore diameter and seated them they should all be the same distance to the lands. i know custom bullets don't vary by much but i have measured one big name makers that do. thanks

 

[tenring]

It would be rare for every bullet to seat at exactly the same measurement ogive to base. Just this morning, I seated 50 30BR bullets made by a well known custom bullet maker with a Wilson chamber seater. I measured every round, and found that depths varied up to .008". I set those aside that I felt were too far away from my desired .005" jam; re-adjusted the seater die and reduced the variance to about .004".

 

[Twoboxer]

You know the answer to your first question since you posed the second question.

If you could measure each bullet's distance between the seater cone's touch point and its bore diameter, that number could be used to adjust each bullet's ("bore diameter") distance to the lands.

 

[Zero333]

I think that wold depend on the seating stem and how far the bullet nose goes into it.

Found that if a box of bullets varies 0.002" from base to ogive, somehow that's the same amount of variance I get from cartridge base to bullet ogive after I load them.

 

[mikecr]

if you sort your bullets base to bore diameter and then seat them will the bore diameter of the bullets all be the same distance from the lands.

Probably not, depending some on your seating force variance and contact quality of the seater stem. From bore diameter to base is meaningless to seating, and pretty much anything else in particular.

if we took the measurement from the bullets in the seater cone to the bore diameter and seated them they should all be the same distance to the lands.

You can compare ogive radius in this manner and cull departures, but this is a limited improvment to seated CBTO accuracy. Factors mentioned earlier still come into play. Remove variance from them, you remove variance in seating depths -as seen via CBTO comparator. If you're somehow trying to predict your distance to lands, keep in mind that bore diameter is probably not the contact point of lands to ogive, and that ogive radius variance will change contact points.
Not suggesting that matching of ogive radius isn't useful, you can pick up a Bob Green Comparator to do it, it's just limited for seating depth woes.

 

[philip brousseau]

thank you for the replies. Mike i looked at the bob green comparator and that is what i'm looking for .didn't know anyone made that tool. trying to tighten up seating depth without having to beat the short ones out with a kinetic puller and reseat. yea bore diameter is not the correct term to use for the point at which the bullet contacts the lands.