FL sizing growing headspace

[Hschweers]

Hi all. Fired my first 6.5 PRC loads, and want to resize and reload. I’m using Lapua brass, hornady headspace comparator with Mit calipers, and RCBS matchmaster FL bushing die.

Fired, unsized brass is pretty consistent 1.643” on the headspace gauge. Moved the ram to the top, tightened the die down and then backed off a full turn, sized. Headspace 1.645”. Moved the die a full turn down to contact shell holder, 1.645”. Moved it down, and down, and down, and eventually got it comically low. Like an inch below the top of the press. 1.645”. I can’t get the headspace to shrink.

OAL grew from 2.021” to 2.0255”

What am I doing wrong?

Thanks

 

[Vern400]

I'm a little bit lost. Once your resizing die touches the shell holder, moving the die downward should result in a cam-over situation. What that means without the brass you should feel resistance as the press goes over center (full upstroke of the ram). You have to be careful with that because I guess you have an almost infinite mechanical advantage and you can break something.

I don't see how you can adjust your resizing die lower than that regardless of what's happening with the brass.

I don't mean to sound bad here but, do you have the right dies? The right shell holder? And does your die have all the parts in it?

On the other hand, is the gauge the right one and contacting the shoulder? Is it hitting something else on the brass, so that pushing the shoulder back doesn't change your reading? By now, if the dye is really doing something your brass should look really funky

 

[BBob]

What am I doing wrong?

Probably nothing. Your headspace could be on the short end, your shell holder could be a touch tall, your die may be a touch deep or a combination of any or all. As you size a case it squeezes the body and initially pushes the shoulder up a touch until the die comes fully down and pushes it back. You most likely need to take a few thousands off the bottom of your die or off the top of the shell-holder so you can size the case a touch more. Shell holders are cheap so sand the top of the shell holder down a few at a time and see if that does it.

Ps I have a couple of die sets here that are like this. Each has it's own shortened shell holder for that rifle and die.

 

[Hschweers]

I'm a little bit lost. Once your resizing die touches the shell holder, moving the die downward should result in a cam-over situation. What that means without the brass you should feel resistance as the press goes over center (full upstroke of the ram). You have to be careful with that because I guess you have an almost infinite mechanical advantage and you can break something.

I don't see how you can adjust your resizing die lower than that regardless of what's happening with the brass.

I don't mean to sound bad here but, do you have the right dies? The right shell holder? And does your die have all the parts in it?

On the other hand, is the gauge the right one and contacting the shoulder? Is it hitting something else on the brass, so that pushing the shoulder back doesn't change your reading? By now, if the dye is really doing something your brass should look really funky

Yeah, I just wanted to make sure I had all the force in the world necessary to bottom it out on the shell holder.

Confirmed 6.5 PRC dies and shell holder. I’ve tried it with and without the bushing and expanding rod (individually and together). All combos of parts/no parts.

Gauge appears to be hitting the right spot. I went to the next smaller size to try that too, and same story (.002” longer).

 

[Hschweers]

Probably nothing. Your headspace could be on the short end, your shell holder could be a touch tall, your die may be a touch deep or a combination of any or all. As you size a case it squeezes the body and initially pushes the shoulder up a touch until the die comes fully down and pushes it back. You most likely need to take a few thousands off the bottom of your die or off the top of the shell-holder so you can size the case a touch more. Shell holders are cheap so sand the top of the shell holder down a few at a time and see if that does it.

Ps I have a couple of die sets here that are like this. Each has it's own shortened shell holder for that rifle and die.

Just sanded .0025” off the shell holder and no dice. I’ll shave more later, see if I can ever get it to do anything.

 

[BBob]

Brass has springback so you’ll have to push it a little beyond where you want it to end up. You’re probably close. Down the road when the brass hardens up after a few firings you may have to push it a bit more.

 

[Bluefish]

The sizing process, push expander ball through the neck, then make the neck smaller, then push the shoulder. On the up stroke the expander ball is pulled through the neck up, setting id of the neck. This could be pulling the shoulder up a little making the measurement longer.
as mentioned the fix is to make the shell holder shorter so you bump the shoulder down more. They are pretty hard, but can be turned on a lathe or sanded. They should be .250” thick. I just had to do this for two different dies when I am forming brass for wildcats. The dies don’t bump the shoulder enough and the bolt was closing tight. Doesn’t take much. .002”-.005” fixed the problem. easy to replace with a new shell holder if you go too far.

 

[doverpack12]

Have you chambered a piece of sized brass with no firing pin or ejector? That will tell you if you NEED to size smaller or if the 1x brass has more growing to do.
Bolt should close with no resistance or as easy as it does stripped with no brass being chambered.

 

[Hschweers]

Have you chambered a piece of sized brass with no firing pin or ejector? That will tell you if you NEED to size smaller or if the 1x brass has more growing to do.
Bolt should close with no resistance or as easy as it does stripped with no brass being chambered.

I didn’t remove any parts from my bolt, but both the unsized and sized fired case chamber totally normally. Has my brass just not grown enough for the die to start working?

 

[wapitibob]

I didn’t remove any parts from my bolt, but both the unsized and sized fired case chamber totally normally. Has my brass just not grown enough for the die to start working?

A typical die will bump the shoulder back way too far when set to hit the shell holder. It's quite possible the brass hasn't expanded enough after only 1 firing. My brass grows .020 when fully formed (7stw nosler brass).

 

[SDHNTR]

Try a different die.

 

[BBob]

both the unsized and sized fired case chamber totally normally. Has my brass just not grown enough for the die to start working?

Possibly. 6.5 PRC from base to datum (@.420 shoulder diameter) is 1.6486”. Reference tools aren’t perfect though.

It can take 2-3 firings to fully form cases.

 

[49ereric]

If your fired brass still chambers why bump the shoulder back?

 

[Caseknife]

Sounds like you are trying to fix a problem that you don't have. The FL die is supposed to resize the fired brass so the round chambers in the rifle and the neck holds the bullet with sufficient tension. If it is doing that, load and shoot.