# Headspace growing???



## Savage260 (Oct 21, 2007)

This is kinda weird, so I thought I would see if any of you had suggestions for me. I am also sending a message to Hornady, so I can see what the "experts" say too.

I am using a Stoney Pt. OAL gauge, Hornady bullet comp, and Hornady Head Space Gauge. When I measure virgin 6mm brass I get a measurement(these may not be the right exact numbers, but the spreads are correct) of 3.769 to 3.771. My fired brass(neck sized in Hornady 6mm die(correctly set up) on a Hornady press with a Hornady shell holder) from my Savage Mod 12 with McGowen barrel measures 3.770-3.771 meaning my headspace is 0.000-0.002 which is pretty good for headspaceing the barrel myself. When I run any of this brass through my Hornady FL die(correctly set up) the headspace measures 3.775-3.778. How is this possible?

This all started when I tried to use neck sized brass fired out of an Encore 6mm barrel from the T/C Custom Shop. I couldn't get any of the Encore fired brass to chamber in my Savage. I ran the brass through the FL die, and still could not chamber it. Then I started taking measurements. The FL sized brass and the Encore fired brass have the same headspace measurements. Am I doing some thing wrong or is there some thing strange going on here???

Thanks for any info!


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## Savage260 (Oct 21, 2007)

Well, at least I got an answer from Hornady. They said the expander was probably making things stretch a bit when pulling out of the die, which is the exact same thing xdeano suggested when I talked to him. He also suggested pulling the expander out and making a "body" die, which I did, and the headspace measurements were the exact same with and without the expander. This suggests to me there is a problem with the die. Any ideas.........any one? chirp chirp chirp.


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## Csquared (Sep 5, 2006)

When your case "grows" relative to headspace dimensions, does the overall length increase proportionately? Also would be curious to hear diameter near shoulder area of brass that would not chamber compared to the brass that chambered.


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## Savage260 (Oct 21, 2007)

Csquared, I was waiting, man what took you so long???

The brass OAL of the neck sized once fired Sav/Mcgowen brass is 2.225. The OAL of the once fired T/C FL sized brass is 2.234. The shoulder of the virgin and once fired Sav/McGowen brass is 0.425 and the shoulder of the FL sized once T/C fired brass is 0.434.

Hornady got back to me again and suggested my shell holder wasn't quite to spec, and suggested turning in the die a little farther. This time virgin brass was 2.225 OAL, 0.425 shoulder, and headspace 3.771. After FL sizing without the expander the measurements were the same except OAL was 2.226, which is good. Although I tried the once fired T/C brass again, and the dimensions didn't change at all before the FL die to after. Is it possible the chamber was just that much bigger than my Sav/McGowen?


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## Csquared (Sep 5, 2006)

OK, I may be missing a couple things, but I think I understand. Simply put, your brass doesn't fit because it's either too long, or too fat. You quickly ruled out too long, and case measurements seem to confirm the T/C fired brass is too fat for the McGowen chamber. Assuming your McGowen chamber is not under-sized, which I highly doubt it is, I'm a little surprised Hornady seems to be somewhat reluctant to admit possible fault. It's not a big deal, but sometimes die bodies are cut at or slightly above the upper range of SAAMI specs, and when you try to chamber a once-fired case (from a different chamber) in a chamber that was cut at the _low end_ of SAAMI specs it doesn't fit. I've machined the bottom of a die body off to allow my case to go deeper into the die to solve this problem before, and my gunsmith tells me that's not all that uncommon. My highly uneducated opinion is that your FL sized brass "grows", relative to headspace AND length, because the virgin brass was stretched during it's first firing, both in terms of length AND diameter. Neck sizing to a neck/shoulder measurement of 3.770 does nothing to reduce the added diameter of the case body. But FL sizing _DOES_ reduce the body, and that relocated brass has to go somewhere, and unless you've been spending even more time in the department's gym than I suspect you have I'm pretty sure you can't push on your press hard enough to duplicate what 50,000 lbs and 6000 degrees did to the case in the chamber, and force the brass back into the case in the form of replaced wall thickness  , so the stretched brass reveals itself as added length.

I don't think you said, but I would guess the second firing of the case had much less affect on dimensions of the neck sized brass. I never get too involved in case dimensions until after they've been fired. At that point I measure everything, as it reflects your true chamber measurements as well as anything short of casting can. Then I know exactly what happens to that case, relative to the chamber, when I work on it.

If I've missed something don't hesitate to point it out, cause I'm still learning this stuff, too!


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## bigedp51 (Jun 9, 2011)

When you full length resize your cases you "CAN" make them "LONGER" if the shoulder is not pushed back properly. The act of squeezing the case in the die causes the shoulder of the case to move foreword until it contacts the shoulder of the die. Went the case contacts the shoulder of the die it is then "pushed" pack to however you have your die set.

The shell holders below are used to prevent you from "OVER" resizing your cases and pushing the shoulder back too far.










The same applies to the resizing die shim washers below.










The purpose of any case measuring gauge is too know the length before firing, after firing and after resizing the case .001 to .002 shorter than actual chamber length.










You can make your cases longer or shorter by adjusting the lock ring or as short as possible by making hard contact with the shell holder. (this could be over resizing depending on the actual head space of your rifle and "WHY" your dies are adjustable)

Having a GO gauge gives you a referance point and a base line "zero" for sizing your cases and figuring out your actual chamber head space. (A resizing die is only "ballpark" and needs to be adjusted correctly)


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## Plainsman (Jul 30, 2003)

Dies should bring brass fired from any rifle into spec if the die is set so your press cams over. If you back away from that you are neck sizing and not full length sizing. At least that is true with run of the mill standard dies. As a matter of fact I had some trouble with the Forester/Bananza Bench rest micrometer set and that was the first question they asked. It turned out to be neck thickness was to much and they reamed out .0025 for me at no charge. My Lapus brass was .015 and the said the 6.5X284 performs best at .013. 
I see two suspects here. A die that is over-sized, or work hardened brass that springs back some. Take an oversize brass and anneal it, then size and measure. If it doesn't fall into SAMI specs send the die back to Hornady.


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## Csquared (Sep 5, 2006)

> The shell holders below are used to prevent you from "OVER" resizing your cases and pushing the shoulder back too far.


Your die adjustment determines how far you push the shoulder back, regardless of what type of shellholder you're using. The main advantage to the competition shellholders is it oftentimes gives you the ability to "cam over", meaning you can set the die body low enough that the shellholder contacts the bottom of the die, which is considered to square the die with the press a bit better. I have a set of the competition holders, but not for the above reasons. I use mine so I can use the same die adjustment for two different rifles, but rest assured perfect die adjustment can be easily accomplished with any shellholder you have.

As to go and no-go gauges, in my opinion unless you're building rifles spend your money on something else. Unless it was made by the same gunsmith that chambered your barrel, a go gauge is only relevant to SAAMI specs, and more often than not, as mentioned above, will only be "close" to where you want your die to be. Fired cases cost you nothing extra, and they tell you everything you need to know about your chamber...if you let them.

Put a fired case (AFTER you've measured it) in the press and run the ram all the way up. Screw the die in until it won't turn anymore. Then lift the press handle. Screw the die in a couple more turns and run the case (lubed) into the die. No need to mess with the lock rings yet. Repeat the process, turning the die in more and more until you see the dark lube line get close to the neck/shoulder junction. At that point I usually turn in 1/4 turn increments, measuring as needed until the shoulder is pushed back a couple thousandths. When I think it's where I want it I put some non-corrugated cardboard on top of the shellholder and run the ram up until it cams against the bottom of the die. Then tighten the lock ring, lower the ram and remove the card stock. The die will be VERY hard to remove when the lock ring is set this way, so I always back the die out and then screw it back in to a repeatable hand tightness. Consequently the second sized case will be ever-so-slightly longer at the shoulder than the one used to set the die. But if the calipers confirm the shoulder has been bumped, the second sized, empty case should chamber with no resistance as the bolt is lowered.

Except for use of a go gauge I agree with most of what was said above. Just wanted to stress how simple it is to properly set-up a sizing die with tools you should already have on your bench.


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