resizing neck .008 or should I use an Intermediate bushing and size twice

[Cameron SS]

I am loading for a .300 WSM. Sammi Spec is .344, and my fired brass measures .343, which tells me I have a pretty loose chamber. My loaded rounds measure .336, which means I should be sizing to about .334 or .335. That means I am sizing around .008 or .009 each time. Once I wear out the factory barrel, my next chamber will be much tighter...

I've read in a couple of places that you shouldn't size more than .005 in one go, and that an intermediate size, maybe .339 or so, should be used.

Does anyone have experience with this? what are the consequences of going straight down to my desired size?

 

[jonbearman]

The only thing I can see happening is work hardening the brass.You can help the case life with annealing the cases about every 3rd firing or so.

 

[sailhertoo]

I'm in the process of stepping down some Norma 300 saum to 7mm and I'm doing it in three steps. But I'm still having some run out issues I can't get rid of. Hopefully fire forming will take care of that.

 

[LCazador]

If your rifle is a repeater you need more than .002 in neck tension , otherwise your bullets will back up into the case with recoil . The best neck tension for a magnum like this is .004 . Use an intermediate bushing and size the necks to your desired dimension , and save wear on the brass .

 

[Cameron SS]

Its not a repeater, its a bolt action.

Using the intermediate step down reduces wear on brass more than just sizing all the down in one go? hmm.

And can you tell me more about the .004 neck tension for magnums? That is the first I've heard of it.

 

[DCRYDER]

Repeaters are not only semi autos. If you are using a magazine then you have a repeater. Loaded rounds in the magazine get pushed forward in the box when your rifle recoils. With magnum rifles recoil, bullets can be pushed farther into the cases if there is not enough neck tension. This is why most factory ammo is crimped.

 

[40X Guy]

Go to German Salazars "Riflemans Journal" and under basics on the left side there is plenty of reading on neck tension and sizing more than .005 on the neck, which he does recommend doing in 2 passes. You can google this or someone will probably post link.

Frank

 

[Cameron SS]

I've read it, and it was quite helpful. My rifle is magazine fed, but I load out past magazine length, so I just fire single shot basically.

My other question is that the redding competition dies allow to determine how much of the neck I am resizing. Why wouldn't I just want to resize the whole neck? I can see why I would want to stop short of the neck/shoulder junction as that can be a point of excess wear, but how much can a few thou of neck sizing one way or the other actually affect fine tuning a load?

 

[RonAKA]

With a large neck you may be better off using a FL die, or a Forester FL that has had the neck opened up so you do not have to use an expander ball. Should maintain concentricity between the neck and body better. See Custom Neck Honing at this link:

http://www.forsterproducts.com/store.asp?pid=30223&catid=19938

 

[308sako]

I have found that annealing and the use of two bushings is a definate advantage when loading for accuracy. You can feel the difference when seating your bullets, and even see a difference in your chronograph results.

As to run out, spend lots of time playing with the orientation of the sizer die, and consider the "O" ring between the lock ring and the press. I normally allow a cartridge case to apply pressure to the die body before locking the die in place, and use enough Imperial case lube.