I thought that since dies seat the bullet by pressing against the ogive of the bullet that you could achieve the same seating depth with different bullets as long as the seating die setting is the same. Ytt I seat two different bullets without reseting the die and the seating depth vavies by .025". Also when I chamber the rounds one chamebers stiff and leaves rifling marks on the bullet while the other does not. Do you see why I'm confused??? Any ideas???

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Any ideas???

Yeah. What you thought is incorrect. You can easily note that the curvey part of the bullets (the ogive) vary in shape and the width of the bullet at the tips vary in width. There's not much consistancy between bullets so no seating punch cavity can make them so.

Adjust for what you want on each type and all will be well.

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Originally posted by Wayfaring Stranger:
I thought that since dies seat the bullet by pressing against the ogive of the bullet that you could achieve the same seating depth with different bullets as long as the seating die setting is the same.

The stem on the seating die is NOT contacting the bullet at the ogive. It contacts the bullet much further up in the bullet nose area, which can vary significantly from bullet type and brand.

Don't forget that each bullet manufacturer has his own idea of how a spitzer bullet should be shaped.
So if you changing bullet brands or even types within a brand, you gotta kinda start over.

You can machine the I.D. of the bullet seating stem to contact the ogive. You whant to?

The bullet's ogive is the entire section forward of the full body diameter to the tip (meplat).

HMMMM, so my assumption was wrong, no surprise, but now whats the best way to deal with seating depth?

Seems like I could just find where the rifleing starts to contact, back off in increments of 0.010" and see which groups best. IS htere a better way?

This is easy to deal with one just has to ajust the seating die to the bullet you are using at the time.

I keep dummy rounds of each bullet style in each die box so when I change bullet style.

I just take the dummy round out put into the seating die and ajust the die to that style or type of bullet Iam using at the time.

Now you are talking about what is the best seat depth. I like mine just of the rifleing.

Some bullets like the soild copper ones barnes tsx ect seem to like more distance. One just has to try it in each rifle to find out what is the best

The "ogive" is that point on the bullet where the taper down from the nose first reaches full caliber diameter, and the shank portion of the bullet begins.

It is this point that a comparitor is designed to measure.

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Originally posted by Slowpoke Slim:
The "ogive" is that point on the bullet where the taper down from the nose first reaches full caliber diameter, and the shank portion of the bullet begins.

It is this point that a comparitor is designed to measure.

See this is the problem. the comparator is not measuring this point or it would be the same on two different bullets. I measured the opening on my comapartor and its not .277 as you owuld expect it to be for .270, its several more like .26 something.

quote:

The "ogive" is that point on the bullet where the taper down from the nose first reaches full caliber diameter, and the shank portion of the bullet begins.

It is this point that a comparitor is designed to measure.

While a "engineer" might call the ogive the point where the curve turns to straight, a tool made to that size would want to slip right over the shank.

While a comparitor may measure (say) .260 the seating punch could well be contacting the bullet at it's .188 diameter. ONLY if the seating contact point and the compairitor contact point are the same, will the 2 be in agreement.

I measure the bullet "ogive" by using the Stoney Point set up. I then start setting my dies up so I repeat that measurement with the seating stem. The stems DON'T seat at that "ogive" point so you just have to adjust as it goes until you can compare your ogive to the sample ogive.

Also remember that not all bullets in the same box are the same length so you have to settle on that one curved point as a measurement as that is what is going to hit the rifling first and the tip length doesn't make a bit of difference unless it is so long you can't get it in the magazine.

Greg