Measured difference b/w Arbor press and traditional dies?

[DrPark]

I have a set of micrometer seating dies but am looking at moving to using the Wilson in-line seaters with an arbor press. Nothing fancy, probably just the basic Sinclair model to start off with. My main question, though, is what kind of accuracy difference should I expect with moving to the in-line seaters versus the traditional die-mounted press (I have both Forster and Redding micrometer seating dies).

Currently, I see a variance in base to ogive of about 0.005" using the micrometer dies.


So, the question I have is, what kind of runout differences have people measured between the two setups and how has that led to changes in group size?

 

[Dave Berg]

Currently, I see a variance in base to ogive of about 0.005" using the micrometer dies.

That is a whole lot. That's +/- two and a half thousandths. When I fine tune the seating depth for a load I go in 0.002" steps. I haven't used anything but Wilson custom dies for a long time but in a batch of 35-40 rounds my base to ogive measured with a Stoney Creek (Hornady) OAL length gauge is +/- 0.001". The custom dies are made by running the chamber reamer into a Wilson blank. I am of the opinion that the variation I do get is caused by slight differences in neck tension.

"So, the question I have is, what kind of runout differences have people measured between the two setups and how has that led to changes in group size?"

I wouldn't expect to get any better runout numbers with Wilson dies than with Redding. When I have runout problems it happens before the seating operation and the seating die doesn't make it any better or worse. I used to sort my match ammo by runout with the worst being around 0.002" TIR measured at the point the bullet contacts the rifling. With the best, hopefully 15 of them, the needle never moved. I've since come to the conclusion that the 0.002" runout shoots just as well as the zeros. German Salazar had an article years ago directly comparing the runout produced by the type of die used. It was pretty inconclusive IMHO but in one case the Redding die actually reduced the runout.

As far as group size, acknowledging I have used nothing but Wilson seaters for a long time, I'm confident that my ammo does not contribute to larger or smaller groups. It does it's job every time and it's the loose nut behind the trigger that causes bullets to go astray.

 

[DrPark]

Thank you. Any tips then on how to reduce the base to ogives I've been measuring? Cleaning the dies? I'm using the Hornady gauge as well. These numbers were mostly from 105 AMAXes. Could bullet variation with Hornady be the issue?

 

[Dave Berg]

Thank you. Any tips then on how to reduce the base to ogives I've been measuring? Cleaning the dies? I'm using the Hornady gauge as well. These numbers were mostly from 105 AMAXes. Could bullet variation with Hornady be the issue?

The bullet could, theoretically at least, contribute to variations. The point on the ogive where the comparator touches is probably not the same as the point where the seater hits so any variation in ogive shape would result in a measured difference. Another bullet thing that can cause variations in base to ogive is if the bullet tip (since you mentioned A-Max) is hitting the bottom of the seater cup which can really screw things up. Easily fixed with some JB Weld inside the cup.

My personal opinion is that neck tension variation is a more likely contributor. When it takes more force to seat the bullet the loaded round will be longer. The cup on the seater stem will slide down farther and also can "dig" into the jacket. Possibly not enough that there's a visible ring but enough to cause a difference in seated length. If you go to a match and see someone with visible rings on their bullets it's a safe bet they won't be on the podium when the smoke clears.

Regarding runout, a number of years ago I had Ken Markel make five expanders for 6MM. Starting at 0.2420" up to 0.2428" in two ten-thousandths steps. The idea was to run the expander in as the last step before primer, powder and bullet and push all the imperfections to the outside. It improved both concentricity and repeatability of seating force (I have one of his arbor presses with the seating force indicator). Didn't improve anything else though so I went back to turning necks. He told me I was crazy and he made them at no charge, probably just to prove a point.

 

[LRPV]

Bullet consistency and brass prep will impact your results more than which seater you are using. The Forster and Redding dies have just as much accuracy potential as a Wilson inline seater in my experience. I like to use the Wilson dies along with a K&M force measuring arbor press as I do weed out some inconsistencies with it from time to time.

 

[1shot]

I have had Redding seaters that were very good, but others just OK. I think the arbor type seaters are better if for no other reason that they are made with my reamer, one at a time, not mass produced. At least I sleep better at night knowing that all my bullets are seated within 3 psi of each other.

Lloyd

 

[/VH]

Case prep that leads to consistent seating force and one of these, in the proper caliber, will get you to a uniform CBTO

http://greensrifles.com/site/mobile?url=http://greensrifles.com/New_Products.html#2784

How it will show up on your targets...I can't predict but I'm betting it won't hurt.

 

[500Stroker]

I have had Redding seaters that were very good, but others just OK. I think the arbor type seaters are better if for no other reason that they are made with my reamer, one at a time, not mass produced. At least I sleep better at night knowing that all my bullets are seated within 3 psi of each other.

How do measure seating pressure in"psi" ?

 

[fguffey]

How do measure seating pressure in"psi" ?

With one of these.

One of these? I have in-line seating dies, when I want to know how much bullet hold I have I use a bath room scale, I place the case on the scale, place the bullet in the top of the case and push down on the seating die with my hand. My favorite seating die design is the die with the hole in the side. The guide in the die centers the bullet with the case neck, some better than others. Herter sold universal seating dies, one die body with a box full of guides.

And then one day I made a bullet seater, no die, just a seater, when it came to centering the neck of the case with the bullet the alignment was absolute.

F. Guffey

 

[1shot]

One of these? I have in-line seating dies, when I want to know how much bullet hold I have I use a bath room scale, I place the case on the scale, place the bullet in the top of the case and push down on the seating die with my hand. My favorite seating die design is the die with the hole in the side. The guide in the die centers the bullet with the case neck, some better than others. Herter sold universal seating dies, one die body with a box full of guides.

And then one day I made a bullet seater, no die, just a seater, when it came to centering the neck of the case with the bullet the alignment was absolute.

F. Guffey

WT? Bathroom scales?

 

[Joe R]

I have a set of micrometer seating dies but am looking at moving to using the Wilson in-line seaters with an arbor press. Nothing fancy, probably just the basic Sinclair model to start off with. My main question, though, is what kind of accuracy difference should I expect with moving to the in-line seaters versus the traditional die-mounted press (I have both Forster and Redding micrometer seating dies).

Currently, I see a variance in base to ogive of about 0.005" using the micrometer dies.


So, the question I have is, what kind of runout differences have people measured between the two setups and how has that led to changes in group size?

One thing I have learned when loading for precision is that many tools that are sold to use as precision tools really aren't as precise as claimed and the user is the last step in the quality control process.

I used to see the same kind of variance in CBTO on my rounds when I used the Redding or Forster seating dies. Then I decided to switch to the Wilson seating die because of the positive stop built into its design. So my seating variance disappeared. But that's not the end of the story.

I use a Wilson seating die with a micrometer. When I first got it, using my runout gage I was able to determine that runout was being introduced in the seating process, but I couldn't figure out how. Then in a conversation with Erik Cortina he said: "Have you verified that your seating die is straight? When reloading for extreme precision you have to assume that the tools are broken and you need to fix them." So that started me thinking in a whole different way.

Well..., I took my seating die to my gunsmith, we put in the lathe and spun it, and I'll be dammed if the lathe didn't start shaving the bottom of die on one side first. After the die was trued up my run out went from 0.005 to .001-.002.

Another nice feature of the Wilson seating die and harbor arrangement, is that when I do seating depth testing, I can load all my rounds long and then do a final seating at the range while testing. That has saved me countless trips and compressed my load development time tremendously.

Kindest regards,

Joe

 

[lawrence97]

If your bto is different after seating bullets, you need to sort your bullets from bto, bearing surface, bob green tool or whatever method you choose. Once they are sorted, a micrometer seater or a Wilson seater should keep your loaded round bto number consistent. I have not seen any difference from using a micrometer head die or a Wilson. When I travel I bring the Wilson and at home I use a whidden micrometer die.

As for the runout, I have not experienced any from a quality seater such as whidden or Wilson.

 

[fguffey]

WT? Bathroom scales?

Yes, bath room scales, bath room scales measure in pounds, if I want to know how much bullet hold my cases have I can use bathroom scales. WHY? I do not have a scale that is calibrated to tensions; I do not have a conversion for tensions to pounds. I can measure the force necessary to seat a bullet and I can measure the necessary force to pull a bullet. I even have tension gages; problem, my tension gages are calibrated in pounds because they measure deflection based on weight.

I have platform scales, I have gold scales, I have Fairbanks & Morris scales etc.; I do not have a scale that measures in tensions.

F. Guffey

 

[500Stroker]

WT? Bathroom scales?

I use a Hog scale.
Only problem I have is trying to get my Mother in Law off of it first.

 

[rardoin]

I use a Hog scale.
Only problem I have is trying to get my Mother in Law off of it first.

Now...that statement can be measured in 'tension'!