Where should the seating die contact the bullet

[jdh47]

I don't think it matters much where the seating plug contacts the bullet as long as it seats bullets consistently. It does matter where the bullet is seated in reference to the throat. As long as I can seat bullets to achieve the CBTO I need for accuracy with little or no run out I am happy and the target is happy as well.

The only other thing you could do is to check and sort the base to ogive of all bullets and load them in batches accordingly.

Joe

 

[Joe Salt]

The only other thing you could do is to check and sort the base to ogive of all bullets and load them in batches accordingly.

Joe

Then why wouldn't you seat off the Ogive ?

Joe Salt

 

[ireload2]

Some BPCR shooters soft seat the bullets in the case necks and finish seating the bullets. Each bullet is seated against the rifling and the final location is determined not by the die but by the location of the lands.

 

[ireload2]

Also i have never seen where a seating stem contacting a bullet farther down the ogive made more runout. Mine contacts a good bit down and i can load with little runout. Now i am using neckturned cases and they are straight after being sized. Matt

Notice that you said little run out and you did not say NO run out. You might get less run out further out on the bullet ogive. It is nothing more than the property of length vs diameter. The longer a bullet is the easier it is to get it straight. I don't think you can ever make the claim that the further down the bullet your seater makes contact the straighter the bullet will be.

 

[dkhunt14]

Notice that you said little run out and you did not say NO run out. You might get less run out further out on the bullet ogive. It is nothing more than the property of length vs diameter. The longer a bullet is the easier it is to get it straight. I don't think you can ever make the claim that the further down the bullet your seater makes contact the straighter the bullet will be.

I am talking .001 or less. I don't think runout is as important as many believe. If you are in the lands in can't help but straighten them.I have shot many great groups at 1000 yards with bad runout. It was one of the things I tested. Matt

 

[Canadian bushman]

I personally think how much contact the seating stem has with the bullet will play a large role in seating straigtness in addition to where it touches.

Ive seen some that only have a very thin ring of contact. I imagine that would allow a bullet to move around a lot ( angularly ) even very high up on the ogive.

 

[mikecr]

My factory seating dies all contact the bullet at about %50 of diameter, maybe less. Where should it contact?

Exactly where it does.

What is the optimal contact location?

<50% of diameter.

Is that "best" if we are not measuring seating depth to that location?

Our measure is tied to our goal. We set CBTO where the gun tells us is best. You don't confirm CBTO with a seater stem. You do so with a CBTO tool/gizzy.

Seater stems contact low on noses to reduce wedging, which would otherwise contribute to variance in seating depths.
Because ogives vary in radius, and seating forces vary wedging, you should confirm desired CBTO with every loaded round.

 

[jfseaman]

@mikecr

I have all the tools to measure but if there is a variance. What do you do to correct?

 

['Freak]

@mikecr

I have all the tools to measure but if there is a variance. What do you do to correct?

A ‘body could run ‘em all through with the seater intentionally set ~ five thousandths longer than the CBTO desired, sort ‘em all into groups based on their initial CBTO, and then finish seating but adjusting the die accordingly making up for the different initial CBTO of each sorted group, so that all end up the same, CBTO.

 

[jfseaman]

A ‘body could run ‘em all through with the seater intentionally set ~ five thousandths longer than the CBTO desired, sort ‘em all into groups based on their initial CBTO, and then finish seating but adjusting the die accordingly making up for the different initial CBTO of each sorted group, so that all end up the same, CBTO.

That would give a reason for "micrometer" seaters.

I have noticed though, that seating is different on "adjustments" to depth. My bullets are hBN coated, neck is usually caliber 0.002 - 0.004 depending on cartridge.

 

[dkhunt14]

I use a Wilson seater and arbor press. I have no trouble keeping them .001. Matt

 

[mikecr]

@mikecrI have all the tools to measure but if there is a variance. What do you do to correct?

I use Wilson neck & seater dies, my bullets are WS2 coated, and I leave the carbon in necks. I also qualify most bullet ogives with a BGC(all in 24 & 26cals).

With qualified ogives I get no variance from target CBTO.
Otherwise, Like dkhunt14, I can see up to 1thou from target. I don't fiddle with that.
If I had a condition where my CBTO varied by a couple thou or more, I'd do like Freak suggested.

 

[noload]

Shooters that understand these concepts of seating are on the top of the food chain. I only seat with Wilson inline and arbor press. I have a BGC and want to omit that step, I push (seat) a .243 Vld with the stem touching at the .240" dia. . I made stems of Teflon,brass, alum, and ss trying to get the right contact so the stem does not grab the ogive and pull the bullet out when its a light tension, I think that seating very close to the land contact area is the way to go if one was to omit the BGC tool and sorting step. I have had some success at seating and getting consistent CBTO, even though the bullets I tested were defiantly out of spec with the BGC. I still have some more testing to do when the weather gets warmer.

 

[jfseaman]

Shooters that understand these concepts of seating are on the top of the food chain. I only seat with Wilson inline and arbor press. I have a BGC and want to omit that step, I push (seat) a .243 Vld with the stem touching at the .240" dia. . I made stems of Teflon,brass, alum, and ss trying to get the right contact so the stem does not grab the ogive and pull the bullet out when its a light tension, I think that seating very close to the land contact area is the way to go if one was to omit the BGC tool and sorting step. I have had some success at seating and getting consistent CBTO, even though the bullets I tested were defiantly out of spec with the BGC. I still have some more testing to do when the weather gets warmer.

Now we are getting into the meat of my post.

If like @noload I/we can seat with contact at or near the ogive, then accuracy of seating depth will improve.

If like @mikecr I/we sort by bullet BTO, seat proud of the target then adjust, accuracy of seating depth will improve.

I do leave the "dry neck lube" moly in/on the neck when I seat to reduce "sticktion" based variance.

 

[fguffey]

I have all the tools to measure but if there is a variance. What do you do to correct?

I am the fan of transfers and standards. I also have the Green sorter organizer from RCBS. I also have the Herter universal seating die bodies with the assorted seating plugs. I have choices and I have 2 inline, angle, butt grinders' I know that makes no sense to anyone but I can grind the length of the seating plug to contact the bullet anywhere I want it to make contact. And then, we all know the contact point between the seating plug and bullet is controlled by the diameter of the hole in the seating plug.

My favorite: Seating dies with holes in the side because there is nothing like a perfect alignment between the neck of the case and the bullet.

F. Guffey

 

[jfseaman]

@fguffey

Can you show me a picture of your "inline, angle, butt grinder". I think I know what you mean.

Can I get a set of expanded pictures of your "Herters universal seating die", I might like to make one. I have ideas.

 

[dkhunt14]

@fguffey

Can you show me a picture of your "inline, angle, butt grinder". I think I know what you mean.

Can I get a set of expanded pictures of your "Herters universal seating die", I might like to make one. I have ideas.

Lots of luck with that!!!! Nobody can get an answer let alone a picture. MATT

 

[fguffey]

Lots of luck with that!!!! Nobody can get an answer let alone a picture. MATT

Matt, that was rather rude of you. There is another reloading forum that has maxed out on socially dysfunctional members. Someone asked about casting chambers; I could say I can not believe they were so rude to him but had I said that I would be lying, I expected it. I apologized to him on behalf of the forum and then contacted him off-line. POINT? There was no one on that forum that could cast a chamber; with one exception. Anyhow, that shooter could not believe it was possible, and those rude members? They still do not know how to case a chamber.

The shooter asked me what was wrong with all of those members on the other forum; I told him they were lonely and threatened by someone that knew more than they did.

And they asked me: "Who do you think you are?" "No one gave you permission to apologies for us".

F. Guffey

 

[dmoran]

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[BoydAllen]

As long as your seater contacts some little distance down on the ogive, I think that that you are good to go. Of course the tip (meplat) should not contact the inside of the seater cavity. Within a given box, bullets can vary as to the curvature of their ogives (which is the entire curve, from meplat to the parallel part of the bullet). This causes variations in the distance between where the seating stem contacts, and where the rifling will contact the bullet. These inconsistencies are one of the major sources of variation in the ogive (actually point on the ogive where a comparitor makes contact) to head dimension of loaded ammunition. The other sources are variation is seating force caused by differences in coefficient of friction of insides of case necks, and variations in work hardening. Given the situation, one thing that can be done is to seat all bullets long, measure and sort them, ogive to head, grouping by how much additional seating will be required to reach the desired ogive to head dimenison, and then adjust the seater for each set.