Neck vs full length sizing

[jrivera408]

Yesterday I neck sized about 20 rounds of .308 as well as about 20 rounds full length sized. After shooting today, I noticed the full length sized brass seemed to shoot better than the neck sized reloads. Keep in mind all brass was was of the same make, trim lengths, and powder charges. Could a difference in neck tension cause the difference in accuracy? Thanks for any input.

[Clownpuncher]

Was the brass previously fired only our of your gun? Neck sizing should only be done on brass that will be used in the same gun it was originally fired from (either as new or from full length sizing).

[Sideline Shooter]

Clownpuncher has a good point. The purpose of neck sizing only is to lengthen the brass life, and get one step higher in accuracy. Also the brass must be shot out of your rifle. This makes the fired brass now custom sized to your rifles chamber. But please note that this ammo should probably only be used for target ammo. The neck sized only cases may be a little stiff to reliably cycle the bolt onto since it was not sized down to loosely fit a chamber.
After a few firings the neck thickness will become thicker from brass flow and neck tensions will start to vary. Then you will have to get a set up ( I don't recall the name, neck turner??) it has a mandrel at a specified diameter and you spin and tighten, spin and tighten the brass basically starts thinning out the neck thickness. Then you must trim the excess brass, trim to length. True, you give up one step in full length sizing just to add a few more steps later! I did this with a .243 target rifle and there was a considerable amout of accuracy gain with this method.
sideline shooter

[John Browning]

Meck sizing really only makes sense in a benchrest rifle when you turn the necks for concentricity.

[general_disarray_prk]

Assuming you're using spent brass that's going back in the same gun it came out of;

* Neck size for bolt actions.

* full length size for auto loaders.

If you neck size only for auto-loaders, you're asking for a stuck case ;-)

[gunboat]

I generally only neck size. Keep cases for each weapon separate.
It is not true that neck sized cases will only fit the weapon originally fired in.
They will fit any chamber somewhat looser than the original.
I have several 30/40's and some cases do interchange, most do not.
Simce I use the same die for fl and neck sizing the neck tension is the same for both.
I presume you use two different dies for fl and neck sizing which could result in different neck tensions.
You would likely get similar results fl sizing with two different fl dies.
my tuppence