Seating die designs

[JFrank]

The wilson seaters for 6 mm have a stem contact point at roughly .174 When I want to compare at that location I use a .17 cal insert on the Hornday tool.

 

[JFrank]

Last fall I switched my seating comparator system to Accuracy One tool.
Rest assured that Wilson seaters are quite capable of .0005 precision without any modifications.

 

[AlNyhus]

Rest assured that Wilson seaters are quite capable of .0005 precision without any modifications.

Absolutely.

 

[DShortt]

I agree, Paul...there's a reason the Wison stems are sized that way.

Making sure the bullet nose doesn’t bottom in the stem is basic stuff and easily rectified. Lapping the stem to the bullet increases the contact area. Again, a simple thing to do.

Good shootin' -Al

I don't understand how lapping would actually work?
Unfortunately, bullet nose profiles seem to vary somewhat.
Am I missing something?

 

[AlNyhus]

I don't understand how lapping would actually work?
Unfortunately, bullet nose profiles seem to vary somewhat.
Am I missing something?

Lapping the stem to the bullet being used gives a wider contact area and minimizes potential jacket damage.

 

[BoydAllen]

As with trimming, given what happens as a round is fired, perhaps seating so that the shoulder is the stop rather than the head might make more sense. I have figured out a way to do this with an arbor press die.

 

[DShortt]

Lapping the stem to the bullet being used gives a wider contact area and minimizes potential jacket damage.

As with trimming, given what happens as a round is fired, perhaps seating so that the shoulder is the stop rather than the head might make more sense. I have figured out a way to do this with an arbor press die.

Guys, I'm still confused.

I understand the idea behind lapping the seating stem to match the bullet, but I’ve also run into inconsistencies between lot #s.

And I don't understand what you mean by seating so that the shoulder is the stop?

I agree that the OAL length of bullets tends to vary quite a bit. So getting away from seaters that contact the upper 50% area of the bullet in particular seems to be great idea to avoid inconsistencies. It seems to me that a seater that contacts the bottom 20% - 30% of the ogive makes more sense?

Perhaps it depends on if you are concentrated on seating depth or self-alignment?

I've checked several seating dies today. They all contact the upper 30% of the bullet.

 

[AlNyhus]

If you want the contact area to be lower, a larger diameter seating stem can be used. On a Wilson inline seater, the seater stem is bullet diameter so this means opening up the die for the bigger seater stem....not that big of a deal to do. The threads in the Wilson seater caps are the same...you just need a different stem. On a threaded seating die like a Redding, a wide variety of seater plugs work with similar thread diameter and pitch.

You'll want to be concerned with both seating depth and alignment. -Al

 

[DShortt]

If you want the contact area to be lower, a larger diameter seating stem can be used. On a Wilson inline seater, the seater stem is bullet diameter so this means opening up the die for the bigger seater stem....not that big of a deal to do. The threads in the Wilson seater caps are the same...you just need a different stem. On a threaded seating die like a Redding, a wide variety of seater plugs work with similar thread diameter and pitch. -Al

Like that seating stem swap idea on Redding dies.

But upon investigation, they use a seater with the same profile on their .243, .260 and .308 sets.

Dang.

I've a Lee set that uses a very simple plug-type seater. Rather than messing with the original, I think I'll make a replacement out of drill rod. Stem is larger than bullet diameter on the .260Rem set at least, so this is a great platform to test.

 

[AlNyhus]

Like that seating stem swap idea on Redding dies.

But upon investigation, they use a seater with the same profile on their .243, .260 and .308 sets.

My Reddings certainly differ for each bullet diameter. The Redding chart shows different part numbers for each caliber.

 

[DShortt]

My Reddings certainly differ for each bullet diameter. The Redding chart shows different part numbers for each caliber.

That's interesting. I literally pulled the stem out of 3 dies. One was a 'Master Hunter' set with the micrometer seating die.

 

[DShortt]

I see no difference in the contract spot on any of the 3 stems.

 

[DShortt]

Right to left. .243Win, .260Win, .308Win.
6.5mm bullets.

 

[DShortt]

All in the upper 20% to 30% area.

I'll go out on a limb. *Maybe* 40% if just looking at the nose.

 

[DShortt]

6mm bullets.

 

[DShortt]

7.62mm

 

[DShortt]

Sure looks like the same seating stem profile to me.
None of which would matter *if* the nose profile remained consistent.
But. They don't.

Maybe if the seating stems actually contacted the bullet in a different location, the multiple part #s would make sense.

 

[BoydAllen]

Guys, I'm still confused.

I understand the idea behind lapping the seating stem to match the bullet, but I’ve also run into inconsistencies between lot #s.

And I don't understand what you mean by seating so that the shoulder is the stop?

I agree that the OAL length of bullets tends to vary quite a bit. So getting away from seaters that contact the upper 50% area of the bullet in particular seems to be great idea to avoid inconsistencies. It seems to me that a seater that contacts the bottom 20% - 30% of the ogive makes more sense?

Perhaps it depends on if you are concentrated on seating depth or self-alignment?

I've checked several seating dies today. They all contact the upper 30% of the bullet.

As long as the tip of the bullet (the meplat) does not make contact inside the stem, very consistent seating can be achieved. At the stage where you are, ignore my remark about the shoulder of the case. That is for last stage experimenters with too much time on their hands ;-) As far as larger diameter seating stems go, that ca be a problem with flat base bullets. A friend bought one that is built that way and it is fine for boat tails, but not for FB bullets.

 

[DShortt]

As long as the tip of the bullet (the meplat) does not make contact inside the stem, very consistent seating can be achieved. At the stage where you are, ignore my remark about the shoulder of the case. That is for last stage experimenters with too much time on their hands ;-) As far as larger diameter seating stems go, that ca be a problem with flat base bullets. A friend bought one that is built that way and it is fine for boat tails, but not for FB bullets.

I can see that. Boat-tail bullets are infinitely easier to seat straight than flat-based bullets.
They act like their own neck expanders.

 

[WSnyder]

I can see that. Boat-tail bullets are infinitely easier to seat straight than flat-based bullets.
They act like their own neck expanders.

A way around that is to use the Lee case mouth flare tool. Even a very small .002" flare makes setting and seating a bullet noticeably easier. The bullet sits nicely and captured on top of the neck compared to no flare.