Neck Tension adjustment

[Shooter13]

my sizing die reduces the neck diameter excessively. Like 6-8 thousandths

Why would you use a bushing that you know is sizing way too much? Honest question.

 

[jepp2]

Why would you use a bushing that you know is sizing way too much?

I never would, that is what the factory FL sizing die (non-bushing) reduces the case neck by. Just excessive work put into the case neck for no benefit other than to make sure the die will adequately size the neck on the thinnest brass made. And that is why I hone them to the diameter I need.

 

[Dimner]

1. Yes, your sizing die reduces the neck diameter while setting the shoulder back and sizing the body, BUT I have found that more recently my sizing die reduces the neck diameter excessively. Like 6-8 thousandths below what I want the neck to be sized down to. Easy to check. Just size a piece of brass with the expander removed and measure the neck OD and compare with a loaded round.
2. Yes, you can just use the expander on the decapping rod in your die to expand the neck. But I have found that if the expander has to increase the neck diameter 0.002" or more - even when I lube the inside of the case neck and use a carbide expander - it WILL pull the neck off to the side and increase TIR of your case neck. Increasing the neck diameter by using a mandrel doesn't induce this runout.

To combat 1. I hone my die necks to the diameter they should be. Using a bushing also accomplishes a similar end point, but I find bushing dies induce more runout than a FL sizing die does with the expander removed.

And I use Lee Collet Dies with the proper size mandrel to prevent undersizing case necks and having to expand them, as well as providing case necks with less than 0.001" TIR. But some folks don't like LCD's and prefer not to use them.

I do not yet have the experience and results to show, but what @jepp2 posted is the route I am taking on three out of four of my rifles with good barrels.

To take a step backwards in the process... I have been working with my FL die and expander mandrels to find the right neck tension (winter paused this project). Then when I have that right tension figured out, that's when I will send my die to Forster to get them honed so I no longer need to use the expanding mandrel.

Long story short, expansion mandrels are for testing neck tension. Then you get the die honed. This is the non-bushing route. I don't compete. I always add this caveat. Would competing change my process? Not really sure. I have no competition rifles or what I would consider competition cartridges. That will change in a few months though.