Consistent bullet seating depth, and why can't we seat off the ogive?

[thefitter]

I am now pretty much 100% certain that seating depth variations are due to bullet inconsistencies.

I have been using a Wilson hand die and a arbor press. With .308 SMK bullets there is a .001-.002 difference in the ogive to tip of the bullet where the die makes contact. I'm now sure of it. It's not neck tension or lack of or too much lube. The Wilson is a straight stop die with no springs and it stops in the same place every time.

Why can't someone design a seating die that seats off the ogive? That's were we take our measurements for seating depth.

I understand that it would have to be a design that does not deform or mark the ogive, but I don't see this issue as rocket surgery.

 

[woolenmammoth]

Ive been wanting to post this exact question for months but Ive only been reloading for a few years and decided to kep my mouth shut. now that its out there though...

 

[LHSmith]

I don't believe bullets can ever be made perfect, not even custom hand made ones. I would venture to say even the ogives vary to some degree. I will argue that on compressed charges you had better have a lot of neck tension, and to play it safe, seat them again just prior to shooting. Sometimes it is desirable to polish the seater stem for a better fit.

 

[hoverp]

Ive never seen any contact from my Forster die than a narrow ring around the bullet ogive...no tip touching or anything in contact other than the small ring on the Ogive

 

[thefitter]

Ive been wanting to post this exact question for months but Ive only been reloading for a few years and decided to kep my mouth shut. now that its out there though...

I just started hand loading in December.

 

[thefitter]

I don't believe bullets can ever be made perfect, not even custom hand made ones. I would venture to say even the ogives vary to some degree...

Ogive to base or tip variations would not affect seating depth if the die sat off the ogive, and you would still always be the same distance off the lands, right?

 

[whiskey08]

hone out your seater, i did two of mine so i could get as close to ogive as i could.

Two good things about it are;

that variations from base to ogives are minimal vs. halfway between tip and ogive.

The other great thing about it, is once my die is set I can change bullets with out touching the die and still be same distance off lands. It works if you changing same brand e.g sierra 175mk to 180 game king, or between berger vld's

 

[necchi]

"I am now pretty much 100% certain that seating depth variations are due to bullet inconsistencies."


Very good, You are now sure. LHSMITH nailed it, they simply can't make mass produced bullets any more closly matched than they already are.
And the minor point differances simply don't matter.
The seating stem does seat off the ogive, buff out the edge a little and any lines left from the stem usually are gone.

 

[thefitter]

"I am now pretty much 100% certain that seating depth variations are due to bullet inconsistencies."


Very good, You are now sure. LHSMITH nailed it, they simply can't make mass produced bullets any more closly matched than they already are.
And the minor point differances simply don't matter.
The seating stem does seat off the ogive, buff out the edge a little and any lines left from the stem usually are gone.

Which seating stem seats off the ogive? Not my Forster Micrometer die or my Wilson micrometer hand die.

 

[LHSmith]

[quote author=thefitter

Which seating stem seats off the ogive? Not my Forster Micrometer die or my Wilson micrometer hand die.
[/quote]

are you confusing the ogive with the pressure ring?

 

[thefitter]

No. Not sure what you are asking me? Pressure ring?

 

[thefitter]

hone out your seater, i did two of mine so i could get as close to ogive as i could.

Two good things about it are;

that variations from base to ogives are minimal vs. halfway between tip and ogive.

The other great thing about it, is once my die is set I can change bullets with out touching the die and still be same distance off lands. It works if you changing same brand e.g sierra 175mk to 180 game king, or between berger vld's

Thanks that's an interesting idea.

 

[sailhertoo]

I don't believe bullets can ever be made perfect, not even custom hand made ones. I would venture to say even the ogives vary to some degree...

Ogive to base or tip variations would not affect seating depth if the die sat off the ogive, and you would still always be the same distance off the lands, right?

Thats the way I see it. And I always wondered the same thing as the O.P.

 

[Steve Blair]

No. Not sure what you are asking me? Pressure ring?

The ogive is the area between the cylindrical bearing surface and the meplat (tip). I have never seen a seating die that did not seat from some point on the ogive. If the variation is really bothering you, buy a Sinclair Bullet Comparator and a good digital caliper and sort the bullets by base to ogive distance. If the meplat itself bothers you, buy a Hoover meplat trimmer and a Whidden pointing die and make them all the same.

 

[thefitter]

No. Not sure what you are asking me? Pressure ring?

The ogive is the area between the cylindrical bearing surface and the meplat (tip). I have never seen a seating die that did not seat from some point on the ogive. If the variation is really bothering you, buy a Sinclair Bullet Comparator and a good digital caliper and sort the bullets by base to ogive distance. If the meplat itself bothers you, buy a Hoover meplat trimmer and a Whidden pointing die and make them all the same.

"The ogive is the area between the cylindrical bearing surface and the meplat (tip)."

Yes but the point on the ogive where the seater makes contact is not the same area of the ogive that contacts the rifling, or where a comparator makes contact. The seater contacts much closer to the meplat.

Also I believe that most of the time the term ogive is used in hand loading it refers to the specific area that contacts the rifling. Not the entire area between the cylindrical bearing surface and the meplat (tip).

Sorting from base to ogive will not fix the issue of the OP. Although it's a good idea for other reasons. Thanks

 

[Martin52]

Forster have just made me a custom seater stem for my BR seating die, it fits the new Sierra 2156 much better than the standard stem - this is a projectile specific solution if you're looking for the best seating solution. You will need to send Forster a projectile sample. Great service from Forster and only about $15.
Martin

 

[infantrytrophy]

Sleepygator is right. The seating dies that I have seen (Redding, Forster, Wilson), have seating stems that contact the ogive, not the tip. The ogive is any part of the bullet's curved surface between the cylindrical bearing surface and the tip (or meaplat, for hollow point bullets).

I disagree with Thefitter. Seating depth variations are not due to variations in the bullets. The die seating stem contacts the ogive, and the bullet base to ogive measurements are remarkably constant.

I did a little experiment a while back, measuring 50 or so .224 Sierra MatchKing bullets. There was quite a bit of variation in the bullet base-to-tip measurements (.009" or so). There was very little (.001 or less) variance in the bullet base-to-ogive measurements. Conclusion: most or all of the variance is in the very tip of the bullets. Sierra MatchKing bullets are excellent bullets; the same variation is present in the other brands of hollow point bullets.

This has to do with the way hollow point bullets are made. It turns out that this variance in the tip of the bullet has some, but relatively little affect on the aerodynamics, except for extreme circumstances such as very long ranges, or for the small differences noted by benchrest shooting.

At any rate, these variations in the tips of the bullets have no effect on the seating depth, because the die seating stem should contact the ogive, not the tip. When measuring the seating depth of a loaded cartridge, it is important to measure from the case head to the ogive of the bullet, not the tip. You need a measuring tool such as an RCBS Precision Mic or a Hornady LNL Comparator. A standard caliper (without the comparator attachment) measures OAL to the bullet tip, not to the ogive.

The above statements assume that the bullet tip does not "bottom out" in the seating stem. Make sure that your seating stem contacts the ogive of the bullet, not the tip. It may be possible for the tips of some very "pointy" bullets (like VLD bullets) to "bottom out" in the seating stem. I'm pretty sure that Redding and Forster will modify your seating stem, for a nominal charge, it this occurs with your preferred bullets.

Randy

 

[bozo699]

thefitter,
This post is meant with all the respect in the world towards you, but by your own admission you have only been loading since December, I have read several of your threads where you were having troubles (We all do) This forum is full of knowledge, (me excluded) and experienced reloaders and shooters, LHSMITH, Sleepygator, and others responding to your posts on this thread are some of the best, I suggest you listen to them and ask lots of questions, also if I may suggest Glenn Zedikers, Handloading for competition is a excellent read and will answer many of your questions, I also agree with Randy SMKs are usually very accurate in there measurments from base to ogive. Here is a link for you and I wish you the best of luck... http://zediker.com/books/handloading/hlmain.html
Wayne.

P.S you have obviously learned a great deal in a short time, it seems in this sport it is a never ending learning process.

 

[Erik Cortina]

I get the same measurement from base to ogive in my loaded rounds regardless of what the bullet measures, therefore, any inconsistencies are pushed inside the case because of the seating die stem contacting at the ogive, and not the tip.

Here's the trick... I take a bullet, chuck it in a drill, then apply IOSSO to the ogive of the bullet and polish the inside of the seating stem with it. Now you have a seating stem that matches your bullet ogive perfectly and will not leave any marks on your bullets!

Hope that helps!

 

[thefitter]

Thanks for the feedback guys. Believe me I am a total rookie. Let me ask my question more precisely.

I'm NOT talking about variables in any of these dimensions:

Base to tip
Base to ogive
Ogive to tip

I'm only talking about two different points on the ogive.

1) The point on the ogive where the seater makes contact.
2) The point of the ogive that contacts the rifling, or where a comparator makes contact.

These are 2 completely different spots on the bullets ogive.

On my 2 dies the seater contacts much closer to the meplat.

All I'm trying to express is that I am seating from one spot on the ogive and measuring from another. And that is why I believe I see .001-.002 seating depth variables. Thanks