neck sizing die bushings

[milboltnut]

The .243 neck dimensions show .276 outside measurement of a fired case hence the chamber measurement.

My lee collet neck die sizes it down to .270...
Looks like it's too much. After I seat the bullet it measures .272....

In order to size the bushing to the correct size for tension, they, Sinclair, says to measure the neck after you seat the bullet and subtract .002 - .003 for the right size bushing.

So from .276 -.002= .275... so a .002 bush, would be the right size bushing?

 

[Old Navy]

If your neck is .276 after firing your chamber is closer to .2775 to .278". How easily can you insert a bullet in your un-sized fired case? Later! Frank

 

[TnTom]

Another method is to measure the neck wall thickness of a case, multiply by two, add the diameter of the bullet and subtract .001". I get a bushing at that dim. and one above and one below. (RCBS)

 

[limbic]

.276 IS YOUR CHAMBER DIA. .272 IS YOUR LOADED ROUND DIA. .272-.002 =neck tension dia. .270. You can't controll the chamber dia without cutting a new chamber with a smaller neck dia. RANDY

What he said. I get three usually..01-.03 less than a seated round.

 

[jo191145]

What rewinder said +1

.276 fired brass is chamber dimension after springback. Actual chamber neck would be .277-.278.

This measurement has nothing to do with bushing selection. Follow Sinclairs instructions.

 

[milboltnut]

What rewinder said +1

.276 fired brass is chamber dimension after springback. Actual chamber neck would be .277-.278.

This measurement has nothing to do with bushing selection. Follow Sinclairs instructions.

I thought about springback later on....

Bullet seating after sizing to determine the proper bushing size doesn't make sense.... neck tension is the key not actual .277-.278... less .001 or 2.

The neck dimensions load manuals give IS the chamber dimensions?

 

[Erik Cortina]

In a .272" loaded round, if you had a .272" bushing, you would have no neck tension, with a .270" bushing you should have .002" neck tension, which is about right.

.276 is your chamber neck diameter. Which means you have about .002" - .003" clearance on each side of your neck when you chamber a round which allows your brass to expand and release the bullet.

Your setup is good, go shoot!

-X3M

 

[whiskey08]

x3mhunter is correct, something else to play with is only sizing a portion of the neck, and leaving a portion at fireformed dimensions, that is supposed to help align the case in the chamber, and less tension on the bullet also helps for consistency

 

[BoydAllen]

Lee collet dies don't use bushings. .002 difference between a sized case and a loaded round sounds about right. To change the neck tension with a collet die, mike the mandrel that the collet compresses the neck against and order a larger one, by the amount you want to decrease neck tension. You need to take that thing apart and see how it works.

 

[milboltnut]

Lee collet dies don't use bushings

I knew that...
I am looking into redding or whoever.....

mandrel.... order a larger one

didn't know that... cheaper to do this...