partial neck turning

I think and tend to agree with L Sherm that people seem to be a little biased towards expander balls. I use Forster dies almost exclusively because they produce the best results out of the dies I've tried and I get very little runout if I use them properly.

First I use a universal decaping die and remove the decaping pin from my sizing dies as well as polish the expander. Next I run the die down on a piece of brass then adjust the expander up till it stops in the neck then give it a half turn back down so there's a little breathing room. Third I tighten down the stem nut just finger tight so it can float. Doing this allows the neck to be held straight in the die neck while pulling the expander through. Using these techniques I produce very straight and concentric ammo.

The downfall of this method is being unable to control the final "up" sizing of the neck with the expander unless you are able to order different size balls to suit your needs.

I'm not implying that using an expander ball is better then a mandrel or vice versa but that if your unable to produce straight and concentric ammo with the expander that there are probably issues elsewhere in your components or methods.
 
or a non floating mandrel fixed to a die body that you could adjust higher or lower to have die body supporting the sides of case

i dunno thinking out loud
 
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rhetorical q

(unturned) if your runout is holding your bullet off centerline of the bore axis , does your jump change due to ogive differences

( turning ) with a nice crush fit closing the bolt on the shoulder wedging into the chamber shoulder angle .. my personal goal is to have no part of that bullet or neck touching the chamber and be as close as possible to equal all the way around

that being said .. if a guy were choosing to not spend time turning .. maybe he might try jamming bullet and leaving an extra .001 - .002 at the shoulder bump ???
 
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rhetorical q

if your runout is holding your bullet off centerline of the bore axis , does your jump change due to ogive differences

with a nice crush fit closing the bolt on the shoulder wedging into the chamber shoulder angle .. my personal goal is to have no part of that bullet or neck touching the chamber and be as close as possible to equal all the way around

that being said .. if a guy were choosing to not spend time turning .. maybe he might try jamming bullet and leaving an extra .001 - .002 at the shoulder bump ???
Whay does that have to do with the OP's original question ?
 
its still on topic .. read it again .. i had to read it twice too ,) i think we're on the same side of discussion anyway

i impied that unturned necks lead to runout ..

IMO using a mandrel only helps when it has been fired after it has been skim turned to be equal all the way around ..

if you just open up a neck with a mandrel without centering the inside of the neck .. the die doesnt hold the side of the case while expanding .. needs to be fired to center that up .. then its off to the races with the mandrel only

that is why i suggested using a high button in a FL die operation before just a mandrel .. attempting to support the case with the FL die, in attempts to have the button pull/correct some inside neck hole over toward center ( without firing ).. i still dont think that will correct it like fire it would .but i think it may move it closer to centerline
 
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I just recently started neck turning because I have been resizing a ton of surplus 7.62 lake city brass down for my 260. This has helped tremendously with the consistency in neck tension and runout in this particular application. Bought a K&M precision setup and I'm very happy with it so far.

What I have been doing is FL resizing with the expander ball and then using the K&M expanding mandrel to push any final irregularities to the outside of the neck, then lastly doing a partial/skim neck turn.

Just as an FYI, my FL resized cases with the expander ball (Forster) will not fit on the turning mandrel on my K&M cutter... I have to run them over the expanding mandrel in order to neck turn.
 
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