Where should the seating die contact the bullet

[jfseaman]

For years we've all been taking "base to ogive" measurements. Seating bullets ti ogive measurements instead of COAL.

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

Where should it contact?
What is the optimal contact location?

I don't mean where does it. I know that. Across brands it's at %50 ish of diameter. Is that "best" if we are not measuring seating depth to that location?

 

[WANTASHOOT]

Great question. . If the surface the seater is contacting has variations that is where the issue will be and should also show up on your comparitor. So it may be different for each brand or type of bullet. I think as long as the die seats the bullet to the same depth it probably doesn't matter much where it contacts

 

[noload]

Great question. . If the surface the seater is contacting has variations that is where the issue will be and should also show up on your comparitor. So it may be different for each brand or type of bullet. I think as long as the die seats the bullet to the same depth it probably doesn't matter much where it contacts

"that is where the issue will be" ......Not necessarily so.

"So it may be different for each brand or type of bullet"...It may be different for the same brand and type.

"as long as the die seats the bullet to the same depth it probably doesn't matter much"....It probably won't seat all the bullets to the same depth.

It depends on how close you want to keep your tolerances.

 

[SheepDog]

This is more of a problem if you are seating bullets in close proximity to the lands. I can see it being a problem for long range match shooters but you can have custom seater plugs made. There is no guarantee that all the bullets in the box have the same length from base to ogive so how many plugs will you have made?
For me, as a hunter, it makes no difference as long as I can shoot to under an inch I am happy. It has been a long time since I used bullet seating depth to get an accurate load. Honestly I typically work the load up with the listed overall length in the manual. I have tried, with little meaningful success, to use bullet seating depth to tune my loads. Adjust the powder charge and go through a few different primers and I can usually find the accuracy I require.

 

[Steve Ladino]

For years we've all been taking "base to ogive" measurements. Seating bullets ti ogive measurements instead of COAL.

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

Where should it contact?
What is the optimal contact location?

I don't mean where does it. I know that. Across brands it's at %50 ish of diameter. Is that "best" if we are not measuring seating depth to that location?

Less contact with the bullet is best so that there isn't any damage to the surface and also to allow the bullet to self align as best it can with the axis of the case neck. Knowing the internal properties of the bullet ( I believe Hollow points are hollow ) for a ways down to some extent anyway so about mid way or close to the point is best in my opinion.

 

[Toby Bradshaw]

I have tried, with little meaningful success, to use bullet seating depth to tune my loads.

You leave a good bit of precision on the table if you don't tune with seating depth. Here's a recent thread, but a search of this site with "seating depth tuning" will turn up many more:

http://forum.accurateshooter.com/threads/rifle-tuning-sr-lr.3914199/#post-36873894

Tony Boyer's book describes a straightforward method for tuning with charge and seating depth. Here's an example of his method in one of my own rifles @ 100yd.

 

[Canadian bushman]

My die contacts a little better than halfway down the ogive.

I make my own comparators, and i make them to the bullet diameter, and to the tangent of the ogive just in front of the bearing surface.

My comparator contacts very close to but not exactly where the lands first touch the bullet.

Where im getting at is: even though my die, comparator, and barrel touch the bullet at three different places, within a given lot of bullets the CBTO measurment is still very close. Typically +-/.001" inside a given lot.

Now lot to lol variations are still a topic of debate.

 

[noylj]

I prefer my seating stems to contact as far down the ogive as possible and NOT touch the meplat at all. Idea is that it is harder to "steer" something from a one-point contact at the very rear, while is gets easier the further forward the steering. It is easy to pull a grocery cart one handed at the front, but a lot more difficult to push the cart with one hand from the rear.
Next, I prefer them to fit the bullet as snug as possible, even if that means a seating stem per bullet type.

 

[SheepDog]

You leave a good bit of precision on the table if you don't tune with seating depth. Here's a recent thread, but a search of this site with "seating depth tuning" will turn up many more:

http://forum.accurateshooter.com/threads/rifle-tuning-sr-lr.3914199/#post-36873894

Tony Boyer's book describes a straightforward method for tuning with charge and seating depth. Here's an example of his method in one of my own rifles @ 100yd.

View attachment 997092

With a close tolerance chamber you may be right, most of the time, but when I'm working with an old 03A3 that has a chamber that is big (around) to start with and a throat that is so deep I cannot touch the rifling with a 180 grain bullet while it is touching the case, tuning with seating depth is an exercise in futility. This is why knowing the gun and its imperfections is necessary before you make blanket statement that may or may not apply. I could rebarrel it but it was my dad's gun, I watched him unwrap it, clean the cosmoline out of it, and finally I watched him night after night rub boiled linseed oil into the stock that he bought semi finished and worked to make it a thing of beauty. It is a piece of my childhood and as long as it will shoot consistent groups under 1" at 100 yards I will continue to hunt with it and put holes in targets. When it no longer does that I'm not sure if it will be hung on a wall or rebarreled but I suspect I will rebarrel it in 3006 and it will shoot for another couple of generations.

 

[LHSmith]

With a close tolerance chamber you may be right, most of the time, but when I'm working with an old 03A3 that has a chamber that is big (around) to start with and a throat that is so deep I cannot touch the rifling with a 180 grain bullet while it is touching the case, tuning with seating depth is an exercise in futility. This is why knowing the gun and its imperfections is necessary before you make blanket statement that may or may not apply. I could rebarrel it but it was my dad's gun, I watched him unwrap it, clean the cosmoline out of it, and finally I watched him night after night rub boiled linseed oil into the stock that he bought semi finished and worked to make it a thing of beauty. It is a piece of my childhood and as long as it will shoot consistent groups under 1" at 100 yards I will continue to hunt with it and put holes in targets. When it no longer does that I'm not sure if it will be hung on a wall or rebarreled but I suspect I will rebarrel it in 3006 and it will shoot for another couple of generations.

I think you need to start reading and applying the excellent advice on this forum offered by some of the best competitors on the planet before you "make blanket statements that may or may not apply". In doing so, you will find a lot of knowledge has been garnered in the last few years in the search for accuracy.

 

[JohnKielly]

I think you need to start reading and applying the excellent advice on this forum offered by some of the best competitors on the planet before you "make blanket statements that may or may not apply". In doing so, you will find a lot of knowledge has been garnered in the last few years in the search for accuracy.

I'm confused. SheepDog suggested, as I read it:

• Blanket rules don't apply to all circumstances.
• You need to know the specifics of the rifle when suggesting options.
• SheepDog has a rifle that the standard bullet for the calibre won't touch the case and the lands at the same time.
  
• The rifle currently shoots MOA (may be subject to proof).

How would competitors' excellent advice apply in this stated circumstance?

 

[LHSmith]

How would competitors' excellent advice apply in this stated circumstance?

Sorry. Perhaps my ignorance about 03/A3 chambers. Will they only accept 180 gr. bullets? IME, changing bullet shape /weight made a world of difference in accuracy on chambers with long throats.

 

[JohnKielly]

It was more the point that a milspec chambering & bore quality isn't likely to be able to achieve a degree of accuracy that custom components & firearms could be expected to.

 

[noload]

I was hoping to learn something on this thread, but I was lured into boredom by some shooters of which this topic does not apply to. It is a shame because I think there is much to be learned on this subject of seating in general.

 

[Ned Ludd]

Knowing exactly where the seater stem contacts the bullet doesn't seem to be of much use to me. Lot-to-Lot bullet variation, or even variation within a single Lot can affect the contact point. Using a standard seater stem versus a VLD stem may also change the contact point significantly. The real key to consistent seating depth is how much length variation occurs between the seater stem contact point and the point on the bullet ogive where the caliper insert seats (i.e. where we take the seating depth measurement). If significant length variance within this region occurs, inconsistent seating depth will be the result. The idea of minimizing such variance by putting the seater die stem farther down in the die so that it is closer to where the caliper insert seats is not new. However, there are a number of technical reasons as to why this is apparently not currently feasible.

If bullet length variance between the seater stem and caliper insert contact points is an issue, one solution is simply to sort bullets by ogive using a tool such Bob Green's Comparator. Once bullets have been sorted for consistent length between the two contact points, the effect of length variance in this region largely disappears, resulting in better seating depth consistency. At that point, the issue of exactly where on the ogive the seater stem contacts is largely irrelevant in practical terms.

 

[ireload2]

Excellent question.
Coming from the stand point of tool designers the contact point should be a functional feature meaning that the stem should contact the bullet on the surface that contacts the rifling to guide the bullet but...
There are really 2 functional requirements for the bullet.
1. It has to be seated to the correct depth. The best surface to contact would be the ogive band that contacts the start of the rifling. This insures a uniform distance to the lands for each loaded round.
2. The seated bullet has to be straight and on axis to the case neck and body. The best way to get the bullet seated straight is contact near the tip. But you would not want to seat with the parts of the tip that may have a variation in shape or location such as the exposed lead tip or a wobbly plastic tip. By using the longest part of the bullet you are better able to minimize off axis condition at the tip.

You cannot really meet both conditions at the same time unless the bullets are perfect and we know the bullets are not perfect.
I guess I prefer to touch the bullet near the tip to keep it straight. Touching back closer to the base of the ogive means that some bullets may be seated crooked.

For years we've all been taking "base to ogive" measurements. Seating bullets ti ogive measurements instead of COAL.

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

Where should it contact?
What is the optimal contact location?

I don't mean where does it. I know that. Across brands it's at %50 ish of diameter. Is that "best" if we are not measuring seating depth to that location?

 

[noload]

I've been experimenting for a couple days now on seating close to the ogive. Trying to omit B. Green comparator step. It's a tuff thing to do.

 

[JohnKielly]

There are really 2 functional requirements for the bullet.

There is a third. The location of the contact between ogive & seating plunger must take into consideration the strength of the plunger material, tolerances & the likelihood that seating into a tight neck and/or compressed load can distort the plunger, as I learned when seating long .30 bullets caused a Redding competition seating die plunger to bell out & shave the cylinder in which it was just short of an interference fit.

Redding did replace the damaged parts without argument but asked me not to use the die for that purpose in future.

 

[ireload2]

Since you damaged the seating punch you might have been close to the threshold of damaging the bullet. If you exceed the yield strength of the bullet your process needs to be investigated to see if the die needs some redesign or you if you need a different powder charge or a different compression method or other cure.
BPCR shooters use a flat ended plug to compress powder. Compressing the powder a half inch or more can distort the bullet nose significantly. That adds another step to the process.

There is a third. The location of the contact between ogive & seating plunger must take into consideration the strength of the plunger material, tolerances & the likelihood that seating into a tight neck and/or compressed load can distort the plunger, as I learned when seating long .30 bullets caused a Redding competition seating die plunger to bell out & shave the cylinder in which it was just short of an interference fit.

Redding did replace the damaged parts without argument but asked me not to use the die for that purpose in future.

 

[dkhunt14]

I'm confused. SheepDog suggested, as I read it:

• Blanket rules don't apply to all circumstances.
• You need to know the specifics of the rifle when suggesting options.
• SheepDog has a rifle that the standard bullet for the calibre won't touch the case and the lands at the same time.
  
• The rifle currently shoots MOA (may be subject to proof).

How would competitors' excellent advice apply in this stated circumstance?

I have yet to see a rifle where bullet seating depth wouldn't change accuracy. Even in a match 1000 yard rifle with the same chambers they will shoot differently with seating depth adjustments. Some guys experimented and found out if they jumped them .100 plus, there was a place they shot better. I never saw this in my guns but most times mine shot good with them in the lands, so I never tried them seated with that much jump. I have also seen where a difference in as little as .003 would take a rifle from winning sized groups to record breaking groups.

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