Checking headspace

[Clem Bronkoski]

Guys (and gals) I'm learning a lot here about precision shooting, especially in regard to reloading. I've been doing this for over 60 years now and I guess you can teach an old dog new tricks.
Like I recently found out that you should not full length resize your brass nor just neck size but rather just bump the shoulder back about .002".
That is all well and good but here's my question: I found out that brass will bounce back a bit so if I have virgin brass should I take a couple and load them up and fire form them to my case more than once, like 2 or 3 times before measuring the headspace in order to get the correct bump then set my sizing die to that or is one firing sufficient?
My rifles are a 6.5CM and a 300WM. Now I realize that because of their design the actual headspace is different. The 6.5 headspaces off the shoulder and the 300 off the belt but for my purposes of bumping back the shoulder is what I'm concerned with for both cartridges.
Inquiring minds want to know

 

[Huntaddict]

Guys (and gals) I'm learning a lot here about precision shooting, especially in regard to reloading. I've been doing this for over 60 years now and I guess you can teach an old dog new tricks.
Like I recently found out that you should not full length resize your brass nor just neck size but rather just bump the shoulder back about .002".
That is all well and good but here's my question: I found out that brass will bounce back a bit so if I have virgin brass should I take a couple and load them up and fire form them to my case more than once, like 2 or 3 times before measuring the headspace in order to get the correct bump then set my sizing die to that or is one firing sufficient?
Inquiring minds want to know

Tons of data on if a guy should full length size or not. For more than 25 years I have full length sized each and every time. It has served me well. I generally bump between .001 and .0015 depending on what the rifle likes.

You should not have to "fire form" brass made for that specific caliber. If you have a SAAMI chamber than OTC brass should fit fine. Yes, after the first firing you should check to see stretch and size accordingly. You will likely get slightly better SD's and ES's after the first run. That should be it. Sure, you can work it more but keep in mind, every time you fire and work brass, you are shortening its life.

 

[Clem Bronkoski]

Sure, you can work it more but keep in mind, every time you fire and work brass, you are shortening its life.

TY Addict....I realize about working the brass and that is why I want to set my die up to only bump back .002" or just enough to have zero feeding issues in my BA rifles. That is the reason I was asking if 1 fire forming is enough or should I do a couple. I may just load all my cases and shoot them then measure and set die then see what happens on additional firings to see if the die needs additional tweaking.

 

[cajun]

Depending on your chamber it may take a couple firings to get the shoulder to chamber length. After the first firing see how the brass chambers. If it the bolt closes easy you can just size the neck.

 

[Longtine88]

do what Cajun said

 

[Clem Bronkoski]

Depending on your chmber it may take a couple firings to get the shoulder to chamber length. After the first firing see how the brass chambers. If it the bolt closes easy you can just size the neck.

do what Cajun said

Sorry guys me along with some champion shooters don't believe in neck sizing but FL sizing and only bumping the shoulder back just enough for smooth feeding.

 

[Phil Rizzo]

Just don't bump the shoulder back until it's needed, to chamber the case.
Let it grow, then bump back enough for reasonable force during bolt closure.
Neck sizing on the 2nd firing isn't a big issue…if you are trying to produce match grade ammo, you don't want to fire cases of different lengths anyhow, I would not think.
It has to finish growth, in YOUR chamber, before consistent bump back can occur.

 

[ARlife4me]

check measurements before and after the case is fired this way you have constant info on what's happening. for me, i just fl size each and every time and never bumped shoulders or measured to see if they were.

 

[Clem Bronkoski]

check measurements before and after the case is fired this way you have constant info on what's happening. for me, i just fl size each and every time and never bumped shoulders or measured to see if they were.

From everything I've read and was told you DO NOT want to FL size every time because it causes work hardening of the brass and accuracy can suffer too because of die dimensions vs actual chamber dimensions. A FL sizing die will size a case so it will fit every rifle in that chambering. FL sizing die instructions say to run die into the press until it contacts the shell holder then lower the ram and turn the die down 1/8 to 1/3 turn more. Doing so would more than likely push the shoulder too far back. That is the reason for using the headspace comparator. So you only move the case shoulder back just enough for smooth feeding.
My question was - should the case(s) be fired a couple times before I get an accurate headspace measurement because of the brass bounce back?

 

[Doom2]

The reality of the situation is you don't know from the case exactly what the headspace dimension is unless the case meets resistance being chambered. This is because of the springbuck on the brass as the pressure in the chamber decays. If you meet little to no resistance extracting the case it's unlikely the case is in contact with the shoulder and bolt face. In the absence of hard extraction and chambering setting the shoulder back isn't necessay. Once you encounter some chambering issues then you can set the shoulder back in increments to set a maximum length for your datum dimension.

There is one caveat on this procedure. It is possible that the hard chambering is not shoulder related but is due to the base of case at the 0.200" area (see SAAMI diagram) expanding and not being resized. This is often a function of the specific reloading die.

 

[cajun]

Sorry guys me along with some champion shooters don't believe in neck sizing but FL sizing and only bumping the shoulder back just enough for smooth feeding.

Point is until the shoulder moves all the way forward you don't need to over size. You said the key thing. Easy chambering. If it chambers easy you don't need to push the shoulder back.
The reason those guys don't tend to neck size is eventually you have to do it anyway and they want consistency. But until your brass is fire formed to your chamber it's a moot point. They also like brass to chamber easily so they don't have issues breaking a firing position.

 

[ARlife4me]

From everything I've read and was told you DO NOT want to FL size every time because it causes work hardening of the brass and accuracy can suffer too because of die dimensions vs actual chamber dimensions. A FL sizing die will size a case so it will fit every rifle in that chambering. FL sizing die instructions say to run die into the press until it contacts the shell holder then lower the ram and turn the die down 1/8 to 1/3 turn more. Doing so would more than likely push the shoulder too far back. That is the reason for using the headspace comparator. So you only move the case shoulder back just enough for smooth feeding.
My question was - should the case(s) be fired a couple times before I get an accurate headspace measurement because of the brass bounce back?

Try telling my Winchester 264wm brass that's been fl sized 25 times. Brass will fail when it decides to regardless of how you reload. I just keep doing what works for me with that brass. Other brands might not last that long and a big reason I buy 1k at a time with same lot. I won't down play or degrade what others do as it works for them.

 

[ARlife4me]

Try telling my Winchester 264wm brass that's been fl sized 25 times. Brass will fail when it decides to regardless of how you reload. I just keep doing what works for me with that brass. Other brands might not last that long and a big reason I buy 1k at a time with same lot. I won't down play or degrade what others do as it works for them.

Also I still get 1moa and better in that same pre64 after 2,500 plus rounds. I was used on p-dogs as I'm not a hunter.

 

[cajun]

T

From everything I've read and was told you DO NOT want to FL size every time because it causes work hardening of the brass and accuracy can suffer too because of die dimensions vs actual chamber dimensions. A FL sizing die will size a case so it will fit every rifle in that chambering. FL sizing die instructions say to run die into the press until it contacts the shell holder then lower the ram and turn the die down 1/8 to 1/3 turn more. Doing so would more than likely push the shoulder too far back. That is the reason for using the headspace comparator. So you only move the case shoulder back just enough for smooth feeding.
My question was - should the case(s) be fired a couple times before I get an accurate headspace measurement because of the brass bounce back?

Thats what we are telling you. What he doesn't mention in the video is they don't do this until the brass is fully fire formed. The case capacity will increase slightly as this happens and these guys want consistent uniform brass.