Yeah, you can tell I'm new at this. Lotsa questions. LOL!

Seems like folks talk a bit about case neck tension. You don't want it so tight that pressures rise, but not so loose that the bullet gets set back further thereby raising tension.

To ensure proper case neck tension do you measure a loaded factory round with calipers and then in slow, methodical changes in depth of seating die you turn the die until you get proper tension?

Thanks..

ARRGH! I meant raising chamber pressures...not tension.

Not sure if you are looking for tension or seating depth but..if looking for tension you can just measure the inside of the case mouth after sizing and hopefully it's about .002-.004" smaller than bullet diameter.

If asking about seating depth you can make up a dummy round out of a once fired....not resized case. Just push the neck on the fired case in far enough so that you can slide a bullet into it with some tension. Then you can hang the bullet out a ways farther than normal and chamber it. If it all works right the bullet will push down into the case and you can measure the overal length of the bullet in the case as it relates to hitting the lands of your barrel.

You don't really have to worry about tension with standard dies. It is built in to the design so no need for you to worry.

If you buy bushing dies then you have to get the right bushings to give enough neck tension. Don't use bushing dies and you have no worry.

Hey RN

Let's see if we can connect the dots here.

Case neck tension is determined by the final inside diameter of the neck. You can regulate this by

• using different bushings in a bushing die, example a.329 bushing
  will theoretically give you .001" more neck tension when using a 30-06 bushing die than a .330 bushing
  
• by honing down the expander ball in a FL die, if you put the expander stem in a drill and hold it against a stone then you can reduce the diameter by .001" or .002" and it will hold the bullet tighter
  
• by honing down the mandrel in a Lee Collet Neck Sizer by .001" or .002"

You can also order smaller mandrels or expander buttons from the die manufacturers.

The seating of the bullet or factory rounds don't really have anything to do with case neck tension. Factory bullets are always crimped and that is their method of ensuring that the bullet doesn't move until fired.

Could you refine you question further?

All I can tell is that if you poke 22 hornet or .25-20 fired brass in a properly dimensioned FL die, neck bushing, expander ball or no, some of those cases will have more neck tension than others. You can feel it in your press handle when you seat bullets. That makes a difference you can see on a target. My belief is that it is due to brass hardness, or "springback" as some say. Others say it magic. For my cases in calibers I noted I anneal every third firing, use a "M" die before seating to feel for the differences, and no longer load large lots as I think aged brass worked too hard splits over time, AND changes tension thus affacting accuracy. But there are other more liberal theories about. Be Careful!

AHA!! All makes perfect sense now.

Actually, I know that by raising and lowering the bullet seating stem that is internal to the bullet seating die you control the bullet seating depth, hence case OAL. However, I was trying to grasp the concept that I could control case neck tension by moving the die itself up and down in the press, vice inside diameter of the resized case. I had thought this would be like trying to effect the roll crimp on handgun cases.

The original question was how much case neck tension is enuff and too much? And how does one tell? And all of you answered it. Thanks.

quote:

Originally posted by RenegadeRN:

The original question was how much case neck tension is enuff and too much? And how does one tell? And all of you answered it. Thanks.

Generally speaking, you have too little neck tension if you can take a loaded bullet, put the bullet end against the work bench and push it in further by using light to moderate force. Don't know if you can have too much bullet tension but if you have difficulty seating the bullet and actually bend the case (usually in the neck or neck shoulder junction) by the force needed to seat the bullet, that would be too much. Once the bullet is seated, firing the charge will create so much pressure that any amount of neck tension will be insignificant.

The main thing is that whatever neck tension you have (as long as the bullet doesn't move), it needs to be consistant.

Sounds to me like you are asking about crimping. Yes, a rifle die will crimp your round if you like. (just like a pistol die)
So I guess in effect you are somewhat controlling the neck tension. Just like a pistol die you can raise the seater stem and screw down the die till it just hits the edge ofthe case mouth and then you will have a bit to play with for how much crimp you get. Crimping will have very little effect on the pressure of your loaded round. I would say the diff between a light case tension and that with a heavy crimp "might" be as much as 3k pressure so unless you are flirting with loads on the edge you wouldn't see a difference in normal shooting.
Some people claim crimping does improve accuracy but others do not seem to find that. It's all a matter of personal preferance. Some who hunt in extremely cold weather like say -10 degrees also think it helps to make ignition more consistant.

For some reason or another I have found that lesser neck tension improves accuracy in my 2506 and 3006 rifles. I used to subtract .002" to .003" from the loaded neck measurement to determine the correct bushing size. That was Redding's initial instructions when I bought my Type S-Match Die set. I then used the die without the expander ball. That way a press fit of at least .002" would be obtained in the necks. Yet my groups improved significantly when I loaded a few rounds with the expander ball in place, that resulted in a press fit of .001" only. I now only subtract .001" to choose the correct bushing to size the necks. Redding has recently (2003) also changed their minds about the best fit. They now suggest you only subtract .001" from the cartridge that had the smallest average measurement. This will allow for a slight amount of spring back and create a proper press fit for the bullet. In my experience lesser neck tension equals better accuracy.