Seating Die design

[PhilKeil]

Seeing the discussion on the seating depth comparator tool. Does anyone make a seating die that will contact the ogive instead of the tip/nose?
Seems to me that would be a more accurate and repeatable way to seat.

 

[Doug Beach]

Your seating die may not reach clear down to the bottom of the ogive, but it should not contact the tip (meplat) of the bullet, at all.

 

[Capt. Oblivious]

If it touches the "tip" /meplate when seating drill the seating stem out so there is no contact on the meplat

 

[PhilKeil]

"Doug Beach
Your seating die may not reach clear down to the bottom of the ogive, but it should not contact the tip (meplat) of the bullet, at all."

"Capt Oblivious
If it touches the "tip" /meplate when seating drill the seating stem out so there is no contact on the meplat"

I understand what both Doug Beach and Capt Oblivious are saying and have done for years, My thought and observation is that from the ogive to the tip of the bullet varies in length.
People go to great lengths sorting bullets, trimming, etc.

Other than a mag feed IE a gas gun OAL does not matter much as compared to the distance to the lands from the ogive.

If a die was made that only contacted the ogive then consistent dimensions could be made and maintained.

Then the oal of a bullet does not matter as much and is there for the ride. I know there is some BC concerns with the tip and shape but that is relatively minor than a big change if you distance to the lands is off.

I made a die once on a wild cat build I did that did what I am saying it worked great. My only issue was choice of materials. It would need to be scaled up some to work on larger cartridges.

Again really thinking along the lines of the tool @BoydAllen and @F Class John posted yesterday. It seems to me we have been so entrenched in the way we have done things for years a better solution is and has been right in front of us.

 

[geo.ulrich]

Yes I made a few with the 1.5 * lead and cut with chamber reamer and adjustable, so bullet engagement is adjusted with throat.....

 

[ronemus]

The geometry of Forster seaters comes close. You have to make the stem strong enough to withstand seating forces, and you need a "contact patch" big enough that bullets aren't deformed; those factors limit how close to the beginning of the ogive the stem touches. The only way to do better is to epoxy bed the contact area, but that means you need a stem (more likely a whole die) for each bullet you shoot. I for one don't want to go there - I'm satisfied with my Forsters.

 

[PhilKeil]

I have been thinking about this all day. I may not be able to put my vision into words but will try.
1st part of inspiration came from story of speedy developing the type S bushing dies.
What if you used a bushing like a neck size bushing that was your barrel bore dia.
I thought of bushings because you can buy pretty much any diameter. This way the ogive is the contact point. And you can control that dimension easily.
I remembered in the bulletin there was a seating die that looks like rcbs competition seating die.
So what if a bushing was in the sleeve that guides the bullet and the case.
Would have to figure out a way for a stem to contact the assembly. But that is doable.
So for operation, place bullet on case like normal, the bullet would contact the bushing at the ogive when raised. When raised the sleeve \ bushing assembly contact the stem and seating is completed.
The seated cartridge would have the consistent lengths in theory. And not dependent of bullets that are the exact same length from ogive to tip.
I am brain storming here trying come up with another way. Not sure if this is what @geo.ulrich made. Has anyone made anything like this before?

 

[geo.ulrich]

Nope made it with a stem .... and supported tip and seated off the throat so if bullets were changed the seating depth stays the same ...

 

[cw308]

It depends on the bullet , RCBS makes a different seating plug for the long distance low drag bullets , most seating plugs work off the ogive. If your setting up your die for measuring OAL it will stop at the ogive but the tip of the bullets will be off, giving you different length measurements

 

[zipollini]

David Tubb addresses this in the design of his 6XC plus dies.

6XC Plus Seating Die

www.davidtubb.com

 

[BoydAllen]

I believe that this comes the closest of any that are commercially available.

http://www.xxicsi.com/calibrated-bullet-seater.html

 

[PhilKeil]

Thank you all. A combination of them both is what I have in my head.

 

[geo.ulrich]

I believe that this comes the closest of any that are commercially available.

http://www.xxicsi.com/calibrated-bullet-seater.html

so if you change bullets or shape you need a different part for seater that will get kind of pricey and confusing ... just saying

 

[BoydAllen]

so if you change bullets or shape you need a different part for seater that will get kind of pricey and confusing ... just saying

Back when March scopes came out, I found it hard to believe that shooters would spend that much more for a scope. When the Bix trigger first showed up, it was the same thing. Evidently I have a pattern of failing to understand the market for premium shooting products.

 

[PhilKeil]

It depends on the bullet , RCBS makes a different seating plug for the long distance low drag bullets , most seating plugs work off the ogive. If your setting up your die for measuring OAL it will stop at the ogive but the tip of the bullets will be off, giving you different length measurements

Since i am single feeding I am trying to maintain consistent seating depth in relation to the ogive/bearing surface to the lands. As mentioned earlier the cartridge oal if not feeding through a magazine does not have much Bering. To me, and I maybe missing something, the 2 things most important is the ogive to lands/jumb and the internal case volume of the loaded round. Both need to be as consistent as possible.

so if you change bullets or shape you need a different part for seater that will get kind of pricey... just saying

Thanks, I bet it does. Which is my point if a bushing like device contacted the bullet and was replaceable it would be cheaper as well as more consistent and accurate.


If i am off on this thought let me know The brain trust and experience here is very deep and I appreciate feed back.

 

[geo.ulrich]

A bushing might work but if you are using the throat angle they will stick, you would need a way to eject the loaded round . it took a little bit of work to come up with a workable design

 

[mikecr]

The 'ogive' is the entire length of bullet nose.
Seater plugs contact roughly 1/3 up the ogive from the mepat (not even close to the tip).
They contact where they do in balance of datum & angle that provides consistent seating, instead of wedging with seating forces.

Seating accuracy is VERY important for bolt guns.
But it doesn't matter what datums you use. Only that you ALWAYS use the same datums that your gun proved as best with testing.

And whether you use standard CBTO or a shoulder datum to an ogive datum (STO) doesn't matter either.
Your shoulders should be bumped to a consistency of well under 1thou, so a difference between CBTO & STO consistency would be within 1thou. Seating windows are greater than this.
It's alotta nothin there..

 

[geo.ulrich]

The 'ogive' is the entire length of bullet nose.
Seater plugs contact roughly 1/3 up the ogive from the mepat (not even close to the tip).
They contact where they do in balance of datum & angle that provides consistent seating, instead of wedging with seating forces.

Seating accuracy is VERY important for bolt guns.
But it doesn't matter what datums you use. Only that you ALWAYS use the same datums that your gun proved as best with testing.

And whether you use standard CBTO or a shoulder datum to an ogive datum (STO) doesn't matter either.
Your shoulders should be bumped to a consistency of well under 1thou, so a difference between CBTO & STO consistency would be within 1thou. Seating windows are greater than this.
It's alotta nothin there..

Your kidding me right ? I am fairly confident I have a grasp on ogives.. I have a graph of 4 different short range bullets. I made 3 of the bullet dies. here are the #'s bullet "a" @ .180 dia. .629 , "b" .652, "c" .625 , "d" .629 @ ,225 dia. "a" .454, "b" .468, "c" .474, "d" .456 , @ 1* 30" angle "a" .219 "b" .263 "c" .251 and "d" .233 there is quite a HUGH difference in ogives. in checking one lot on a comparator there is a difference from bullet to bullet. If you think seating depth is greater than .001 perhaps you should discuss this with the Short Range H.O.F. points leader you are sadly mistaken . this is what I love about forums so much bad information being thrown out......

 

[PhilKeil]

Thank you all

 

[cw308]

From your closed bolt to datum line measurement will remain the same , and the closed bolt to ogive will change from use . Only small adjustment in the seating stem and you good to go , I check my CBTO every 500 rounds when using the same bullet and lot #. Any changes in bullet , may require adjustment to the seating stem to receive the same jump , jam or touch. Pretty cut and dry without confusing matters.