Neck sizing question...

[SeaRun1]

So I bought one of the Hornady caliber neck sizing dies.  The kind that cover the whole range of bullets of the same diameter.  In this case it is a 7mm Neck sizing die.

The directions are not 100% clear to me.  I tried sizing using the direction in my RCBS dies and just crumpled the case.  Followed the directions for the Hornady dies and it worked much better.

My question is that it says move the die down and size as much of the neck as you need to.  Wouldn't I always want to size the entire neck just short of the shoulder?  I figured out an easy way to adjust the die right to the shoulder but was still confused.

Is there a need to always neck size the entire neck?  Why would I only partially size the neck?  I guess I am a little unclear on this and I can't get the answer I need from my three reloading manuals.

Thanks for your help.

SeaRun1

[JimmyHoffa]

The best answer I've always heard was related to pressure and placement.  Some of the benchrest guys like to just barely have their bullet set into the case.  So they use the minimal amount of contact area.  They think it produces more consitent pressure and by having the neck still partially fire formed, the bullet will have more consistent alignment.  The other extreme is full neck resize and crimp, which is thought to build a little more pressure.  From the test results I've seen the crimping usually had less deviation in pressure.

[fremont]

I have Hornady sizing dies in 6.5 and 7mm and always size the entire neck.  However, these are hunting loads.  (And, before someone says you must full-length size every hunting load, I chamber check each one before going into the field.)

[SeaRun1]

OK thanks guys.  I guess I was just kind of unsure why a guy wouldn't do the whole neck as opposed to just a portion of it.  I guess I still am a little confused. 

SeaRun1

[Heredoggydoggy]

You don't mention case length in the reloading process.  "bottleneck" rifle cases grow longer with each firing, depending on the chamber they are fired in, a little or a lot.  Cases that have stretched beyond maximum spec. will crumple in a die, usually  the seating die.  If you are reloading rifle cases, a case trimmer is a must!  Neck sizing will slow the rate of stretch, but the neck sized reloads should only be fired in the same gun.  (you probably already know that tidbit.)

[SeaRun1]

Yes I did.  I do measure the fired cases to make sure they are under the maximum trim-to length.  Again where I am confused is with this specific neck sizing die.  I have all RCBS or Redding dies and the neck sizing die that I use for other calibers works differently and no problems have surfaced.  With the Hornady die it is caliber specific and so sizes any of the 7mm calibers.  A completely different set of directions which allows for a varied amount of neck sizing to occur.

SeaRun1

[Heredoggydoggy]

Hmmm.. Not familiar with the Hornady neck sizing die.  Does it have changeable collets so it can be tailored to the thickness of the brass or is it a one size fits all die?  I've used the RCBS and Redding neck sizing dies with no problems at all.  The only Hornady dies I have are the .450 Bushmaster dies, because they were the only ones making them.  The only complaint I've heard from guys using the Hornady dies is the rubber washer on the seating die doesn't hold the adjustment, and to take it off and throw it away.  I've had no problems, but the .450 is a big straight-walled case and is more like loading pistol cases.  Maybe bottleneck cases are more touchy in that area.  I'm curious to know what is causing the problem.  Please report back if you figure it out.