OzFclass

Hi brains trust,

All the projectile seating dies I have seen index up the pill a long way away from the ogive.

Why is that? Do any use the ogive as the index reference, and if not, why not?

I would of thought that using the ogive would be more accurate than some other measurement near the tip that seems to have no relevance.

I hope you can shed some light on this.

Cheers,

It rather depends what we are calling the ogive.
There is a tendency to make the ogive the circumferential line where the front of the bullet achieves the maximum diameter. If that's what you mean, the reason you can't use it to seat is because if you applied any force the seater would slide down the bullet because it is at max diameter. Another common belief is that the ogive is the circumferential line where the bullet achieves the diameter of the lands. This is the point we generally measure to with the comparator
So what actually IS the ogive? It's the whole front section of the bullet, so really all seaters do seat on the ogive. So why dont we seat from a point close to that max diameter or at the lands circumference? There is an advantage of seating from a different point to measuring. If the bullets are seated consistantly but do not measure consistantly,,,, the bullet ogive is not consistant and you should think about batching.

Wilson does a VLD seating stem to achieve the result you are discussing.

https://lewilson.com/vld-drift-seating-stem

Phil,
F Class Products make what you want
https://fclassproducts.com/arbor-press- ... m-upgrade/
The 7mm version fits my Wilson dies, I presume the 30cal will also fit a 308 die.

I think this only matters if you are changing bullet type or batch and you don't want to remeasure, as the seating die engagement point should be consistent if the bullets are uniform
Pete

Wasn’t my question but these are some great answers guys.

https://appliedballisticsllc.com/wp-con ... esigns.pdf

As @Tim L above, you can't make a seater stem with ogive /bearing surface junction diameter (eg. 0.243 with a 6mm pill) as the seater would just slide down projectile under press force.
So die manufacturers nominate a smaller diameter and that hits at a different point on the ogive, depending on model of bullet and ogive design.

Thanks for all the replies.

I understand now.

Cheers,

By having the projectile seater engage with the projectile closer to the tip it makes it easier to ensure the projectile is concentric with the case and your loaded round straighter.

Yes you still need to check it, but it will be a lot straighter to start with and easier to straighten without a lot of fuss.

A projectile that does not engage the lands straight will come out of the muzzle just as out of alignment as when it went in the chamber. "Wobbly" bullets induce yaw in the flight of the projectile and yaw is bad for the group size.