Home Forums Reloading Big Game Rifles Help me understand neck sizing for the 338-06

Ok, so I have a 338-06 and want to try neck sizing my brass to see if my accuracy get better with neck sized cases and to lengthen the life of my brass. Before I order a neck die is there a way to neck size brass to see if this will help my accuracy or if my gun is shooting as good as it can (or that I can).
I have read that I can neck size by simply adjusting my FL sizing die so I only size the necks. Is this true? If so, why would I buy another die? What are the pros and cons of sizing that way? And how do I check that I am doing it right?
Secondly, if a neck die is only sizing the necks why couldn't I take my lee collet neck die for the 30.06 and replace the mandrel with one for a 338 WM or other 338 caliber?
And if I do buy neck sizing dies for the 338-06 what should I order? Is it worth the time to get the custom neck die from Lee? Thanks!

I make my 338-06 brass from once fired 30-06 brass.It's cheap enough that I don't worry too much about extending the life of my cases.I tried neck sizing 30-06 brass with a Lee Collet Die about ten years ago.It was nice to just neck the brass and load,but I didn't see the accuracy I get when I full length resize,even noticed some cartridges were tight when chambered.I look back and I'm sure some brass was fired more than others,so the hardness of the brass varied greatly causing different neck tension and maybe that could have been affecting accuracy.I have decided I'd rather full length size,keep my brass in groups by the number of times fired and after about four or five firings make the decision on annealing it or if issues start showing up on numerous cases,just get rid of it.

Jesus just back the die off 3/4 of a turn and check to make sure the cases chamber allright.

If you set the full length die correctly, that is to bump the shoulder back only about .002", then you won't have brass life issues. The rounds will also chamber smoothly the same way every time.

I do exactly what math man states above. You can back your full length die out so it barely bumps the shoulder. Will chamber fine without excessive working of the brass. I try for 1-2 thousanths.

Everyone (even the rude ones) has given correct advice.
Nobody has answered your question about getting a .338 mandrel for Lee collet die. I don't know all about how these work but that would sure be worth a call to Lee and asking them. If correct, that's a cheap and easy way to achieve what you're looking for as well (neck sizing only), as there will actually be some body sizing if you just back off the FL die to only touch the neck. Same for just touching the shoulder (though they are right that this is a great goal to adjust your die to. After a couple firings neck sized only you will probably need to bump back the shoulder anyway.)
I frequently find my loads are less concentric, which is so bad for accuracy, when I have only neck sized (in an actual neck sizing die, not a FL die backed off), but you can always adjust concentricity later with a Tru Angle tool or similar.
A good piece of advice to make your brass last longer, especially if you are necking up 30-06 or necking down .35 Whelen to make your brass, is to anneal at first and then every 3-4 firings. Lot's of guidance on 24CF on how to do that for cheap.
Minimizing the sizing as the other respondents have suggested will help case life too.

Best of luck. I own two 338-06s now and like them very much.

Cheers,
Rex

A 338 mandrel won't work with a 30-06 collet. The radius of the circular cutout in the tips of the 30 Cal collet is too small.

Damned, I didn't even see any rude comments. I didn't even post anything on this thread yet either.. I usually just shake my head and laugh... Its like watching you guys as little kids trying to jump on a spinning merrygo round and getting flung off... Funny chidt..

Agreed, I tried to run some 7mm Rem Mag brass thru my .264 Win Mag LCD. It didn't work.

out of curiosity , and since i have no way of measuring, how many turns is that on a standard fl die?

You can't really figure it from the thread pitch since brass is springy.

yup, adjust it so it will just be sizing the neck... or pick up a Lee neck Collet die...

for a 338/06 body die, pick up a 35 Whelen F/L sizing die and take out the spindle and decapping pin...

if not by thread pitch how do you do it?
i would imagine that the brass spring issue suggests that each brand and each lot of brass will be different .

thank in advance

Back the die out 1/2 dozen turns, run a case through it and see where the neck stops. You'll see a little hump. Keep turning the die in a little at a time and running the brass through. You can watch the neck ease down to the shoulder. You should be able to tell when you kiss the shoulder.

Color your case with a sharpie.

Move the die down until neck is fully resized and the body of the case isn't.

Jamison's rule of 1/4 turn of a die equaling 1/16" of an inch isn't too far off. Usually.

Exactly what he said. And your accuracy will be as good or better..