Case Neck Runout

[Lachdanon]

What is the best method to prevent bending the necks when expanding 6.5x284 norma Lapua Brass to 7mm X 284?
I have been using K&M expanding mandrels with the windowed riser in a Harrell's combination press.
I have tried expanding in 1 through 3 steps and I still get increased run out in my expanded cases.
I do not tighten the mandrel in the die nor the die in the press I leave a both just a little loose hoping that this would fix my problem but to no avail.
My lot of cases run from .001- .003 (a few are straighter) right out of the box after I expand them
they run from .0015 -.0065 (a few are straighter and a few are .0075)
This may be normal but I have been ashamed to ask.
Thanks in advance for your attention?
Glenn

 

[Richard Coody]

shoot them. they will straighten right out.

 

[Bart B.]

Try gently gripping a bulleted case neck in a 31 caliber collet in a bullet puller. Gently bend the case body such that the case neck is straight. A few trials can show how much force is needed pushing on the case head.

I've done that with commercial and military 30 caliber match ammo with .003" and more bullet runout in a 33 caliber collet. Always shot more accurate.

 

[dmoran]

@Lachdanon
I use the same setup (K&M w/window-riser <> o-rings to float both the die and mandrel) and have no issues inducing runout at all. As a possibility: maybe the alignment issue is on the other end, such as the shell-holder (squareness or obstruction), or something else.
Good Luck

 

[BoydAllen]

You do not want things floating when you are expanding up from one caliber to another. I can say this because the absolute worst results that I have had expanding .220 Russian cases up to 6mm was when I tried using a Forster press. The best results were with a Harrell's Combo press. that has tighter than normal die threads and very close alignment. I have several of the K&M expanders and although they work ok for expanding at the same caliber for turning, the best that I have tried for expanding up is one from PMA Tool that has a very long taper. The other trick that I can share is to do something akin to what is called peck drilling when you are expanding up. Advance the expander slowly into the neck until you feel the pressure increase to a point that you will have to determine by experimentation, and the reverse the ram slightly, taking the expander out of contact with the ID of the neck, and then go again. By doing this several times during the expanding of one neck, using a good lube and a mandrel with a long taper I think that you will solve your problem. Doing it this way I can expand .220 Russian cases up without making them any more crooked than they were right out of the box.

 

[dmoran]

You do not want things floating when you are expanding....

I do.... and know others that do as well.

 

[BoydAllen]

How much end of neck runout do you start with, and how much after expanding? Do you expand up. or are you expanding to turn at the same caliber?

 

[dmoran]

Amounts before and after: hardly any measurable amount, and unchanged after (or I would do it different).
For all expanding (neck turning, false-shoulders, necking up, neck tension).

 

[CTanM]

Runout.....

Heavy sigh..........

 

[Lachdanon]

How much end of neck runout do you start with, and how much after expanding? Do you expand up. or are you expanding to turn at the same caliber?

You do not want things floating when you are expanding up from one caliber to another. I can say this because the absolute worst results that I have had expanding .220 Russian cases up to 6mm was when I tried using a Forster press. The best results were with a Harrell's Combo press. that has tighter than normal die threads and very close alignment. I have several of the K&M expanders and although they work ok for expanding at the same caliber for turning, the best that I have tried for expanding up is one from PMA Tool that has a very long taper. The other trick that I can share is to do something akin to what is called peck drilling when you are expanding up. Advance the expander slowly into the neck until you feel the pressure increase to a point that you will have to determine by experimentation, and the reverse the ram slightly, taking the expander out of contact with the ID of the neck, and then go again. By doing this several times during the expanding of one neck, using a good lube and a mandrel with a long taper I think that you will solve your problem. Doing it this way I can expand .220 Russian cases up without making them any more crooked than they were right out of the box.

I am expanding up from 6.5mm to 7mm I have not checked the run out on the end of the case. if you are talking about the end of the neck?
I did lock everything up tight with some locking rings and it helped most are .0015- .003 a few are less.

 

[BoydAllen]

Yes, the end of the neck.

 

[Shynloco]

I do.... and know others that do as well.

+1. Works great for me with runout consistently under .02 and rarely over .02.

Alex