Full length sizing after that stretch!

You mean the CBTO is not changing as you screw in the die? Post some pictures of die in the press. And the die and lock ring.

When you zeroed on a once fired brass that had not been sized, was your spent primer still in the case? If so, it is possible your spent primer might have some slight catering or sitting proud that it's giving you a long measurement. After sizing, which is also decapping, you will now get a correct measurement of the brass itself that does not take into account a proud primer or cratered primer.

Dumb question but are you zeroing out the calibers after each measurement?

If yes stop you are bumping the shoulder way too much.

First firing of virgin or factory brass doesn’t require bumping the shoulder. It takes about 2-3 firings for the brass to grow to max chamber. Size the brass and neck but don’t bump the shoulder. When the bolt drop gets heavy it’s time to bump the shoulder as that will be your headspace.

Remove the firing pin from the bolt and chamber the fired case. Does the bolt handle drop easily on the fired unsized case? If yes size the body and neck only don’t bump the shoulder. Fire another time and do the same process. When the bolt handle doesn’t close easily it’s time to FL size and bump the shoulder till the bolt handle closes.


Fire the case again and measure again by putting the fired case into the chamber without the firing pin. If bolt drops freely size body and neck but don’t bump the shoulder. Repeat till the bolt handle doesn’t drop.


if the bolt doesn’t drop freely take that measurement that is your rough headspace. Size the case till the bolt drops freely. Probably start about 3/4 turn out size take a measurement. Keep sizing and adjusting the die in very small increments till you get a -.002 from original fired case using your comparator kit. Properly sized fired case will allow the bolt handle to drop freely. Go slow so you don’t over size the case.


Check out the wheeler method of determining headspace.




Here is another step by step that covers a lot about reloading. Check out part I and Part 2

Once the die is seated on the shell holder firmly you’re not going to get any more sizing by screwing it in further. You may have to experiment with shell holders or take a few thousandths off the mouth of the die. They make shell holder kits for this. The die will have to be done on a lathe I would think.

Will the sized brass chamber in your rifle without applying bolt force to do it?

Make sure the primer is out before you measure the fired case as the primer will add length to the measurement. Just extend your decapping pin so that it kicks the primer but doesn't start to size the case.

Wipe all the lube off the case before measuring after sizing.

Mysavageisaccurate said:

It stretched
That is the point

Click to expand...

If the shoulders are not being bumped back, it is quite possible that your brass "stretches" at the shoulder as you FL size. You are squeezing in the body of that piece of brass, and the brass has to go somewhere. The first place it can go is to the shoulder if there is space there for it to move in to. There is space if your die is not screwed down enough.

Sounds like your chamber is short and the die is unable to push the shoulder back at all.

What you’re seeing is normal. Your chamber is incompatible with your die.

Mysavageisaccurate said:

Yeah of course i think about the primers that may affect the length

So just by using neck sizing die
Decapping of once fired brass
And check the length and amazingly same
If i put and processing into FL die
It stretched
That is the point

Click to expand...

How about trying this: remove the spindle with the expander ball and FL size a case and see what you get? Report back what you get. (yes, the neck will not have been expanded, but we're trying to narrow down what the cause of your issue is)