run out question

[BoydAllen]

What kind of sizing die?

 

[MildBill]

What kind of sizing die?

forster neck sizing die

 

[BoydAllen]

It has been my experience that one piece neck dies produce the worst runout of almost any die. The runout in necks, that is the result of sizing, is generally an angular divergence from the CL of the case, and when bullets are seated they extend that angle, so that the farther that you measure runout from the neck shoulder junction, the greater the reading. The key to all of this is the sizing die. If you use a Lee collet die, it will probably give less runout, or if you have you Forster neck die lapped out by Forster to a dimension that leaves little work for your die's expander to do that should help. Try this experiment. Remove the expander assembly from the die, size a case, and compare the OD of the neck with one that was done with the expander in place. Let us know what the difference is.

 

[sigma2chi]

I was having runout issues until I completely removed the expander ball and trashed it. Now I size without the expander and never have more than .002 MAX runout.

 

[BoydAllen]

The problem with that approach is that a bullet can only be expected to do a certain amount of neck expansion without running into concentricity issues. What do your necks measure after sizing, and after bullets are seated.

 

[bigedp51]

1. What make/type gauge are you using to measure your run out?
2. Do you have a gauge setup that can measure case wall thickness and base run out?
3. Have you tried other brass/case brands?
4. Have you tried partial and full length resizing?

If you have a bad batch of brass with unequal case wall thickness your cases could be warped and banana shaped and thus causing your run out and accuracy problems.

NECO CONCENTRICITY, WALL THICKNESS AND RUNOUT GAUGE
http://www.neconos.com/details.htm

Also referred to as "The Case Gauge," this item is designed to measure:

1) The curved "banana" shape of the cartridge case;
2) The relative wall thickness variation of a cartridge case;
3) The cartridge case head out-of-squareness;
4) Individual Bullets - out-of-round "egg shape" and/or
curved "banana" shape (excepting very small bullets);
5) The seated bullet and cartridge runout of loaded rounds. The accuracy of any firearm is determined -- and limited -- by the quality of the ammunition shot in it. The effect of imperfections in ammunition is cumulative; each flaw adds to the influence of all others. Precision shooters spend much time and effort "uniforming" cartridge cases, using advanced techniques to eliminate variation. Yet until recently, one of the most important of these variations has not been susceptible to detection by any device readily available to marksmen.

 

[boltman223]

Wow how did you get your cases to float haha

 

[boltman223]

I had run out issues with my 223 using my forster seating die. So I called forster, it turned out that the seating die I had was purchased before they switched their standard seating stem to the vld seating stem. The way you can check this is take your stem out and put your bullet in the stem. The bullet will wobble and you will be able to see that the bullet is not making contact all the way around. It might be a good idea to check anyways, if you haven't already.

 

[Raythemanroe]

+1

 

[MildBill]

it was with a Sinclair concentricity instrument

I do not have an instrument for measuring neck wall thinkness yet....

I have had the same problem with groups when I used Winchester brass.

I have a forster bushing bump die, but was going to take things one step at a time and get things dialed in smoewhat before figuring that thing out.

I have some lapua brass that I was saving till I had stuff somewhat sorted out with loads.

 

[BoydAllen]

What I was looking was the outside diameter of a cases neck after sizing and with the bullets seated. This should be measured at the same place on the neck since the OD changes, on unturned necks, as you get farther back from the case mouth.

 

[MildBill]

What I was looking was the outside diameter of a cases neck after sizing and with the bullets seated. This should be measured at the same place on the neck since the OD changes, on unturned necks, as you get farther back from the case mouth.

ok

on neck sized with button left in 0.270

on neck size with button assembly removed 0.2645

no bullets seated in either.

with bullet seated they appear to be about 0.2715

 

[BoydAllen]

Thanks, that was what I wanted. IMO you are getting some runout by using the seating of the bullet to expand the neck from .2645 up to .2715, .007. One thing that you could do is to have Forster hone out the neck portion of your die. With unturned necks, you would want to leave a little for your expander to do, possibly have the die opened to .268, and then the drag of the expander shouldn't do much to your neck concentricity. If at that point you would like some more neck tension, you could polish down the diameter of your expander ball. Using a dry lube on the necks, something like Imperial, would also smooth the expander, without contaminating powder. One little improvement that has made a noticeable difference in the concentricity of rounds that were made with either Redding Competition, and Forester seaters is to shorten the sliding sleeve so that it is raised by the case and does not make contact with the shell holder when a case is in place. Ogive to head uniformity can be helped by setting up the die so that the very lightest of toggles can be felt when the ram hits the top of its stroke.

 

[338 Mollett]

Rich at sierra gave me this tip. take a fender washer about one inch in dia. with a .250 hole in the center place it between the shell holder and die apply a little pressure with the ram and tighten this will true up the ram and die together.I took a mic. to the hardware store to find one true they thought I was silly they don't appreciate our passion lol Might help !

 

[338 Mollett]

Also you can index your cases and rotate them accordingly that helps sometimes. This works on sizing and seating dies.Good luck !

 

[boltman223]

Thanks, that was what I wanted. IMO you are getting some runout by using the seating of the bullet to expand the neck from .2645 up to .2715, .007. One thing that you could do is to have Forster hone out the neck portion of your die. With unturned necks, you would want to leave a little for your expander to do, possibly have the die opened to .268, and then the drag of the expander shouldn't do much to your neck concentricity. If at that point you would like some more neck tension, you could polish down the diameter of your expander ball. Using a dry lube on the necks, something like Imperial, would also smooth the expander, without contaminating powder. One little improvement that has made a noticeable difference in the concentricity of rounds that were made with either Redding Competition, and Forester seaters is to shorten the sliding sleeve so that it is raised by the case and does not make contact with the shell holder when a case is in place. Ogive to head uniformity can be helped by setting up the die so that the very lightest of toggles can be felt when the ram hits the top of its stroke.

Why don't you just get a bushing die?

 

[MildBill]

Thanks, that was what I wanted. IMO you are getting some runout by using the seating of the bullet to expand the neck from .2645 up to .2715, .007. One thing that you could do is to have Forster hone out the neck portion of your die. With unturned necks, you would want to leave a little for your expander to do, possibly have the die opened to .268, and then the drag of the expander shouldn't do much to your neck concentricity. If at that point you would like some more neck tension, you could polish down the diameter of your expander ball. Using a dry lube on the necks, something like Imperial, would also smooth the expander, without contaminating powder. One little improvement that has made a noticeable difference in the concentricity of rounds that were made with either Redding Competition, and Forester seaters is to shorten the sliding sleeve so that it is raised by the case and does not make contact with the shell holder when a case is in place. Ogive to head uniformity can be helped by setting up the die so that the very lightest of toggles can be felt when the ram hits the top of its stroke.

the seated bullet neck measurement was seated into a casing that was neck sized with the button, not without.

shorten the sleeve or just set up the die higher so the sleeve does not touch the base when at the press is raised to the top during the bullet seating procedure?

i did check the bullet seating cup in the die, and someone had mentioned, and it is such that it makes good contact all the way around.

 

[BoydAllen]

Since the thickness of the neck and the diameter of the bullet remain the same, the OD of the neck of a finished round should not vary regardless of whether the case was sized with or without the expander in place.

IF you observe the process carefully, does the shell holder push the sleeve up into the body of the die, when seating a bullet, if it does, what I was suggesting was a slight shortening of the sleeve so that it does not touch the shell holder, and the case pushes the sleeve up in the die body. This cannot be modified by simply raising the die in the press.

 

[MildBill]

Since the thickness of the neck and the diameter of the bullet remain the same, the OD of the neck of a finished round should not vary regardless of whether the case was sized with or without the expander in place.

IF you observe the process carefully, does the shell holder push the sleeve up into the body of the die, when seating a bullet, if it does, what I was suggesting was a slight shortening of the sleeve so that it does not touch the shell holder, and the case pushes the sleeve up in the die body. This cannot be modified by simply raising the die in the press.

yes the sleeve touches the base and pushes it up some into the body, the directions that come with it indicate to set it up that way.

 

[Raythemanroe]

Thanks, that was what I wanted. IMO you are getting some runout by using the seating of the bullet to expand the neck from .2645 up to .2715, .007. One thing that you could do is to have Forster hone out the neck portion of your die. With unturned necks, you would want to leave a little for your expander to do, possibly have the die opened to .268, and then the drag of the expander shouldn't do much to your neck concentricity. If at that point you would like some more neck tension, you could polish down the diameter of your expander ball. Using a dry lube on the necks, something like Imperial, would also smooth the expander, without contaminating powder. One little improvement that has made a noticeable difference in the concentricity of rounds that were made with either Redding Competition, and Forester seaters is to shorten the sliding sleeve so that it is raised by the case and does not make contact with the shell holder when a case is in place. Ogive to head uniformity can be helped by setting up the die so that the very lightest of toggles can be felt when the ram hits the top of its stroke.

Boyd, can you explain the shortening of the sleeve because my Forster ultra is do to be here Tuesday and I would like to set it up right!