Neck sizing with a mandrel, or bushing

[golfer2b2000]

I have been a fan of the Redding "S" dies for some time now. I have used them on my 30BR,6BR, and also a 6PPC. These have all been a tight neck case.
I am going to start reloading for the 6mm Creedmoor. Shooting it from a chassis platform, with a magazine. This will be a no turn neck. I was going to invest in a S die for this also, but got to thinking that since it's a no turn neck, and quite possible I will be using, and trying different that it might be a better idea to use a mandrel to size the necks because I am sure that the brass will not always have the same thickness.
I understand that this is not a bench gun, but still want accuracy. I also don't want to be neck turning all my 6mm Creed casings.
Any thoughts??

 

[chromatica]

I use a Wilson FS bushing die to size my brass. Then I use a Lee Collet die to expand the necks to a consistent diameter. The Lee Collet die is a mandrel with petals that close down around the outside of the neck.

 

[skeeljc]

I used to use a Redding S FL bushing die to bring the neck down to .002 under final diameter and then used a mandrel to set the final size. This method produces consistent inside diameters with variable neck thickness. Now I turn necks and do not expand. This saves time and produces the same result. If your brass has consistent neck thickness within .0005" total variation you can just size the OD and not expand.

Skim cutting the necks (70-80 percent cleanup) is worth the effort because you only need to do it once and you can eliminate an operation when prepping your brass.

 

[D-4297]

In having a "No Turn" neck chamber , your only concern should be interference fit being consistent . As @skeeljc said above , the "S" Die followed by the expander will give solid results . I tried turning necks using a NO Turn chamber , and it made thngs worse , so I went back to my old way . I use a bushing that only moves the brass a minimum amount , so the expander isn't trying to move the world , just a half thou.

 

[chkunz]

I used to use a Redding S FL bushing die to bring the neck down to .002 under final diameter and then used a mandrel to set the final size.

This is what I do also.

 

[markm87]

I use the collet over mandrel dies for the very reason that I usually have several kinds of brass in each caliber.

That, and there's low runout compared to an expander ball or bushing die in my experience.

 

[mikecr]

Mandrel expansion takes care of several matters.
It drives thickness variance outward -away from seating bullet bearing. Good for reducing loaded runout.
It sets residual spring back energy to an inward energy, providing consistent tension over varying lengths of time (a general expansion benefit). And mandrels do not offset or stretch necks like buttons can.

I'm likely not the first to use mandrels for reloading neck expansion, but I am the first to bring it to shooting forums (over 20yrs ago). The benefit I 1st struggled to convince folks about was lower loaded TIR.
As far as adjusting neck interference, I never seen this as benefiting from mandrels. Instead, I adjust tension via neck sizing length (instead of interference), using bushings.
But I always pre-seat necks with a mandrel.

 

[209jones]

The advantages of using a mandrel to expand became pretty obvious the first time I used a Lyman M die for cast bullets. At the time I`d bought a few different custom sized 2 step ones from Buffalo Arms to experiment on neck tension on cast bullets. Slapped myself upside the head and said why the heck did I wait so long to try this. Just makes life much simpler, always used motor mica with sizing dies, but, dumping the button was still a total pleasure. Not 100% convinced on bushings yet, still playing with them.

 

[MSS]

I use a collet die and bump the shoulder when I need to. I have recently been testing the Whidden bushing die.

 

[Alex Wheeler]

I use bushings only. Even on no turn stuff.

 

[Straightshooter1]

In having a "No Turn" neck chamber , your only concern should be interference fit being consistent . As @skeeljc said above , the "S" Die followed by the expander will give solid results . I tried turning necks using a NO Turn chamber , and it made thngs worse , so I went back to my old way . I use a bushing that only moves the brass a minimum amount , so the expander isn't trying to move the world , just a half thou.

I tried this technique using a couple of bushing dies and couldn't get neck runout any better than .002" to .0025 TIR. I went back to using my FL dies that were honed out to give me that minimum of movement after using an expander mandrel where I'd consistently get <.001" TIR. Whether that makes any significant difference on my paper, I don't really know. In any case, since my reloading goal is to produce as uniform cartridges as I possibly can, I'll stick with a non-bushing FL die that's been customized plus expander mandrel.