Headspace grows after full-length sizing? Am I bumping the shoulder correctly?

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adrenaline681

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Yesterday I purchased a Hornady Headspace comparator and I started taking some measurements. On my fired 308 brass the headspace was on average 1.622".

After setting up the FLS die how Lee recommends (screw until touches the shell plate plus 1/4 more turn) and resizing my shell it measured 1.624" is not a huge change but for what I understand the resizing die is supposed to compress the shell back to SAAMI specs and when its fired it expands to match the chamber.

1) Is it normal that it grows when im using the sizing die the way is instructed in the Lee manual?

I read a good way of getting reliable precision is to do a 0.002" shoulder bump so I screwed the die a bit more and I was able to get the headspace to 1.620".

2) Am I doing this correctly? Fired size 1.622" - 0.002" then the headspace after resizing should be 1.620"

I know there is a huge debate between only neck sizing for bolt action vs full-length sizing, but I want to know if I'm bumping the shoulder by 0.002 correctly and if I should expect an increase in precision by doing this.

I also read some people like to use the collet neck sizing die after the FLS die to make sure the neck is perfectly rounded. I also read some people like to do it before FLS.
3) Do you guys think this be helpful or an unnecessary step since I'm FLS already?

Thanks!
 
Adjust the die lower and it should push the shoulder back more, most dies when they contact the shell holder and the press cams over the case should fit in any chamber.

Just remember as the case is sized and squeezed smaller in diameter it grows in headspace length until the case shoulder is pushed back down by the die.

And if you are full length resizing there is no sense in sizing the neck again with a Lee collet die. Some people use a body die and then size the neck with a collet die to reduce neck runout.

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A Lee full length die uses a collet to grip and center the expander in the die, and their die can produce very concentric ammo. So just keep turning your die down a little at a time until you get the desired amount of shoulder bump.

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Answer for question 2 - only your chamber knows for sure. Many of us have been reloading for years and have never bothered with headspace gizmos. Before you get too far with this you should try one of your resized brass in the chamber.
 
When full length sizing and then using a collet die as a second seperate step, people are using Redding body only dies. The Redding body only die resizes the body only and does not touch the neck of the case. This 2 step process keeps concentricity very good over several reloadings.

Bumping .002 does not increase accuracy but will also not hurt accuracy. The main purpose is to have the same sized cases every time. And also to have reliable chambering. Just neck sizing works only for so long before you run into chambering problems.

When you resize and bump .002 yes your case will grow in length. When squeezing the case back down the brass flows out towards the neck increasing it's length.

If headspace is increasing that means you have not scewed the sizing die down quite enough yet. If your fired brass is 1.622 and after sizing goes to 1.624, the case is getting squeezed back down and therefore increasing in length. You are just on the brink of hitting the shoulder and bumping it back. Keep running the die down very small amounts at that point until you hit 1.620. When you get the die screwed in enough to actually start bumping the shoulder you will "feel it"
 
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I find the Redding competition shell holding set quite handy in achieving the repeatable head spacing results that I want

“The Redding CompetitionShellholder Kit #1 consists of five shellholders in varying heights with increments of .002". Allows you to increase or decrease the case to chamber headspace without adjusting the dies”

https://www.redding-reloading.com/online-catalog/35-competition-shellholder-sets
 
Whidden makes a click-one thousands adjustable die ring.
Once had a rifle where the Forster FL die would not size the shoulder back far enough so had a gunsmith shorten in lathe.
 
What type of press are you using?

What type of lube?

you are correct in that when sizing for headspace, the die should produce "shorter" headspace brass after sizing. Variables that can affect your actual result is the press, shell holder and lube.

you are not going insane... there is just a quirk you are not seeing in your setup.

Jerry
 
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