Neck sizing question

[Allen]

While looking for a neck sizing die set at a gun show this weekend, I was told I could use my Full Length dies to only neck size. To do this you just back the die out a 1/4 turn. Is this true?

I get brass from other people so I want to resize it before using in my rifle. After firing in my rifle I just want to neck size the brass.

Allen

[Jack]

Well, kinda sorta, not really.
If you back your full length sizer out 1/4 turn or more, you are setting the die to not push the shoulder back much, if at all (depends on how far you back out the die). Try it, and you'll see on the case neck, an area near the shoulder that was not resized. You also are still sizing the case body to some degree.
Using the above technique is called partial sizing.
To get true neck sizing- defined as sizing the full neck and nothing else- you need a neck sizing die.
When you use other folks' brass in your rifle, you'll need to full length size first. After that initial FL sizing, you can use partial sizing, or use a neck sizing die and neck size.
Partial sizing is thought to make the brass you've fired in your rifle fit the chamber more closely. And it does work, as long as you don't back the FL die out so far that you don't size enough of the neck to grip the bullet sufficiently.

[Rocky Raab]

The downside of partial sizing is that gap at the shoulder. When you size the neck and some f the body, the brass wants to "go" somewhere, and that somewhere is into that little gap. Partial sizing invariably results in pushing the shoulder even farther forward than does firing. I have had cases that would not chamber or chamber only with difficulty after being partially-sized, because the shoulder had been pushed forward.

The only cartridge where I've had success with partial sizing has been the Hornet, and I suspect that its shoulder is so shallow that it "thinks" it is a straight-wall case. Every cartridge with a typical shoulder that I've tried reacts poorly to partial sizing, in my experience.

I use the die as it is designed. FL dies are adjusted to fully size the case and set the shoulder. If I ever wanted to neck size (and I don't), I'd get dies designed to do that and that alone. If I were to make a recommendation, it would be for Lee Collett Neck dies, because they apply force only perpendicular to the case axis and never push or pull the neck. Thus, the shoulder is completely unchanged.

[Adam Helmer]

Allen,

You got good advice to your question. If you get your friend's brass, full length resize it. I custom size all my reloads for a specific rifle and note it on the packing slip with the reloads. I back off my resizing die a quarter turn, or so, for all my rifles and then try the sized brass in the specific rifle. If it doesn't chamber with only a slight "crunch" fit, I lower the sizer die a bit and try again until it chambers easily.

I have used this technique for all my Garands, three Match M14s and all other rifles for years without a problem. Last week a buddy asked me to load him some .300 Weatherby ammo when he dropped off the dies and cases. I told him I needed his rifle to set the sizer die. He dropped off the Remington 700 yesterday, so now I can proceed. There is no need to oversize rifle brass: doing so will shorten 7mm RM brass case life. The .303 British brass is another round that can do with minimum case resizing. I keep an info sheet in each die box listing how far to back off the sizer for individual rifles that is confirmed at the bench with the rifle handy.

Adam

[Allen]

I have been very busy this past week and just now got to read all of your replies. Thank you very much for the information, it will help me down the road when I start working with my rifle ammo again.

Allen

[Catfish]

There is 1 other problem you may run into. I have run into it with over sized custom chamber but not with a factory chamber yet. That is if your chamber is lagre you will not only partical size the neck but also the body of the case. When you size the body of the case much you will have a ring that runs just a head of your die. If you push it clear to the back of the case you will clean it up, but if not the ring may keep your rounds from chambering.