FL resizing or neck sizing with a FL Die

[BJung]

Decades ago, it was vogue to neck size a case than FL resizing it. This even included partially inserting your FL die to just resize the neck. Is this still valid? If not, why?

[NoSecondBest]

I'm wondering how you can neck size only on a FL sizing die? It's got to be a real trick with a bottle neck case. You can partially size the top of the case, but it's not really neck sizing only.

[5whiskey]

Yeah I second the above^. If you are using a FL die, in order to size the neck at all you have to run the case far enough up into the die such that the body is also sized.

I have a theory on why neck sizing was once quite popular. It is just a theory, and I may be completely off base. Lee, which has a significant market share of serviceable reloading equipment, went to great lengths to proclaim the virtues of neck sizing with a collet die in “modern reloading.” I honestly believe the reason why is because it is not at all difficult to describe in writing how to make accurate ammo with a collet die. It’s almost dummy proof. Turn the die in until it touches the shell holder, or whatever setting it was. It is much more difficult to describe how to set up a FL die for making accurate ammo. That’s my theory anyway.

Neck sizing is a very easy way to size cases. Only problem is, if you want more than 3 or so firings from a case you will have to FL size at some point.

[zplinker]

Nosler at one time advocated partial sizing, using a full length die, maybe still do. However, it will cause the shoulder to rise, and after a few time doing this, you will find it hard to chamber that case. That can be useful, to determine exactly where to set your full length die; partial size a few cases, load and fire, repeat 2-3 times, until they chamber hard, then take your die down until they just close w/o tension.

[BJung]

To neck size, I lube the neck with say Imperial Wax. Then I start to screw down the resizing die and watch the lube rubbed off until I get to the base of the neck where it meets the shoulder. The theory behind it is that the case has been expanded to your chamber and is the best fit for your rifle now.

[Bart B.]

Two Sierra Bullets' employees deserves the credit for proving proper full length sizing fired bottleneck cases headspacing on their shoulder best centered case necks on shoulders producing best accuracy. This happened in the late 1950's. They honed commercial full length sizing die's neck out to a couple thousandths less than bullet diameter and tossed the expander ball. Dies were set to push case shoulders back a thousandth or 2 so bolts closed freely into battery repeatable for every shot.

One if them was a tool and die maker in their shop; Ferris Pindell, one of the "P's" in the PPC benchrest cartridge family that's been popular since then. The other was Martin Hull, their ballistics test manager who was also a top ranked match rifle competitor in NRA's high power disciplines.

Rimless bottleneck cartridges center their shoulders perfectly in the chamber neck before the round fires regardless of how much body or neck clearance there is to the chamber. The bolt face ejector does that before pulling the trigger and the 2 ounce firing pin moving near 20 fps pushed by near 27 pounds of force does that after the trigger is pulled.

Good quality new cases often produce better accuracy than neck only sizing.

[old roper]

Having shot BR with 6ppc which was not SAAMI spec case and was reformed Sako 220 Russian case. Myself I neck sized back then. Today you have to reform Lapua 220 Russian case so still not SAAMI spec.

I guess one of the "P" learned how to wildcat working at Sierra.

[Bart B.]

Originally Posted by burbank_jung

To neck size, I lube the neck with say Imperial Wax. Then I start to screw down the resizing die and watch the lube rubbed off until I get to the base of the neck where it meets the shoulder. The theory behind it is that the case has been expanded to your chamber and is the best fit for your rifle now.

If that's done with a regular full length sizing die, the case body is also sized down. Mic the body diameters before and afterwards to see the difference.

[hounddawg]

when the ram is fully raised the entire body of the case is fully supported by the walls of the die . The neck and body are being squeezed by the walls of the die and in effect it is being cold extruded. When the ram is being lowered the point where the expander ball is dragged back through the neck the body is not supported. Misalignment of the body and neck can only occur at the time the case body is free floating inside the die

[Bart B.]

Originally Posted by hounddawg

when the ram is fully raised the entire body of the case is fully supported by the walls of the die . The neck and body are being squeezed by the walls of the die and in effect it is being cold extruded. When the ram is being lowered the point where the expander ball is dragged back through the neck the body is not supported. Misalignment of the body and neck can only occur at the time the case body is free floating inside the die

Yes.

Some have set expander balls a few thousandths below case neck with the ram topped out. This let's the expander start enlarging the neck with most of the neck still in the die. Sometimes does pretty good. But at the expense of work hardening the neck twice in one resizing operation.