Consistant seating depth...

[marine52]

I believe I did, but maybe I just don’t get how the shoulder gets changed with out the washer .

Without washer there is no pressure on shoulder and no possible change. I measured my bullet central 308 win micron arbor die and there is a 0.015 distance between mouth of die opening and case base when case is pushed against die shoulder. THE MOUTH OF THE DIE RESTS ON THE BASE PIECE. Without washer, the base of case also rests on the base piece and there will be a gap between the case shoulder and die shoulder. Die manufactures set this distance so the die will work on all SAAMI spec chambers/cases.

The washer is .062 thick. So when the washer is glued to the base, the case is forced into contact with die shoulder and the die mouth no longer rests on the base piece. This means that the seating is indexed off of the case shoulder while the force of the arbor press is now on the stem and case shoulder. Normally the seating force would be on the mouth of the die

 

[JFrank]

Without washer there is no pressure on shoulder and no possible change. I measured my bullet central 308 win micron arbor die and there is a 0.015 distance between mouth of die opening and case base when case is pushed against die shoulder. THE MOUTH OF THE DIE RESTS ON THE BASE PIECE. Without washer, the base of case also rests on the base piece and there will be a gap between the case shoulder and die shoulder. Die manufactures set this distance so the die will work on all SAAMI spec chambers/cases.

The washer is .062 thick. So when the washer is glued to the base, the case is forced into contact with die shoulder and the die mouth no longer rests on the base piece. This means that the seating is indexed off of the case shoulder while the force of the arbor press is now on the stem and case shoulder. Normally the seating force would be on the mouth of the die

Thanks, I’m starting to see the benefit. What diameter washer are you guys using?

 

[marine52]

Thanks, I’m starting to see the benefit. What diameter washer are you guys using?

I just grabbed one out of my toolbox that looked right. It’s a quarter inch center hole with OD of 0.63”.

 

[Evan]

Thanks, I’m starting to see the benefit. What diameter washer are you guys using?

If you drop a case into your seater die (turned upside down) and measure from the base of the case to the base of the die, you’ll need your washer to be thicker than that measurement. You can also test fit the washer and make sure it isn’t contacting the die when it’s resting on the case. I use a washer with a 0.5” OD that is pretty thin. My base to base measurement was only in the neighborhood of 0.020”, and the chamfer on the entrance of the wilson dies is huge so a wide range of washer diameters will fit.

 

[JFrank]

If you drop a case into your seater die (turned upside down) and measure from the base of the case to the base of the die, you’ll need your washer to be thicker than that measurement. You can also test fit the washer and make sure it isn’t contacting the die when it’s resting on the case. I use a washer with a 0.5” OD that is pretty thin. My base to base measurement was only in the neighborhood of 0.020”, and the chamfer on the entrance of the wilson dies is huge so a wide range of washer diameters will fit.

Thanks Evan,
Working with the 6 br seater the diameter of a dime is close, I noticed also while marking the case shoulder with a sharpie the die only made contact with the neck shoulder junction on virgin brass. I’ll have to check it with FF brass but a curiosity.

 

[Webster]

I checked the seater stem last night when I got home from work, inspecting it with a magnifying glass and good light.
There were clearly no cracks on the stem, I then turned it over and put a bullet in the stem pressing down on it and still no seperations.
Next thought is to try some other brands of bullets, I have some Bibs to try and some Barts.

Erik Cortina has a video where he anneals brass then measures seating presure with a gauge. After annealing the seating pressure varied somewhere around 10-20 lbs. No uniformity. Pushing harder might make the seating cup move a little farther down the ogive? I would think the distance of the bearing surface to the rifling is what's important. That should have some affect on the shape of the pressure vs time curve. The pressure isn't determined by where the tip is. Bullet jump determines approximate bearing surface to rifling then we use a method to seat bullets based on that measurement. Short range shooters shoot extremley small groups by measuring jump then seating with a die that must be like what all of us are using. A lot of SR shooters are using neck wall thickness around 0.0085" so they have less tension to force bullets in the case. Sorry if I am wandering but these are things I thought of.