Head space +

[Link]

I recently got some used brass [7mm mag] it has excessive head space. Like .015 to .020. If it will fire with just the primer it should fire a loaded round?? I don't want to jam the bullet as it has to fit the mag. I will buy new if my shop has it tomorrow. Doubt it lol.
Thanks for your time, Don.

 

[358WCF]

Doesn't 7 Mag headspace on the belt? If you're worried about case stretch, neck them up to 30 then resize with the 7 Mag die until they chamber. There may be a small visible hump where shoulder meets neck before firing.

 

[Link]

Doesn't 7 Mag headspace on the belt? If you're worried about case stretch, neck them up to 30 then resize with the 7 Mag die until they chamber. There may be a small visible hump where shoulder meets neck before firing.

Didn't know about headspace at the belt. Maybe I will shoot them and fire form to chamber?
ty

 

[M-61]

Didn't know about headspace at the belt. Maybe I will shoot them and fire form to chamber?
ty

Every belted magnum headspace’s on the belt for the first or second firing of the cartridge. After that the headspace is from the closed face of the bolt to the datum line on the shoulder.
The datum line is an imaginary line on the sloping shoulder.
Where did you come up with your numbers? What did you measure?

 

[Link]

Every belted magnum headspace’s on the belt for the first or second firing of the cartridge. After that the headspace is from the closed face of the bolt to the datum line on the shoulder.
The datum line is an imaginary line on the sloping shoulder.
Where did you come up with your numbers? What did you measure?

I measured datum line to head - face. I checked some that I resized , they measure .004 headspace. The unloaded bolt drops with verry little effort. I believe the qizmo that attaches to my calipers is made by Hornady.

 

[Bill K]

Headspace is still measured at the belt,

Every belted magnum headspace’s on the belt for the first or second firing of the cartridge. After that the headspace is from the closed face of the bolt to the datum line on the shoulder.
The datum line is an imaginary line on the sloping shoulder.
Where did you come up with your numbers? What did you measure?

on belted cartridges. But after firing the brass is also now formed into that rifles chamber, for the rest of the cartridge life. Resize and reload according to your chamber therefore. Trim length. etc as necessary.

 

[Dkk37058]

Where’s Guffy when we need him

 

[M-61]

Headspace is still measured at the belt,

on belted cartridges. But after firing the brass is also now formed into that rifles chamber, for the rest of the cartridge life. Resize and reload according to your chamber therefore. Trim length. etc as necessary.

I think we said the same thing?
My problem was if his measurements are right we’re looking at a .015-.020 stretch and that stretch will come from right in front of the belt. Belted magnums have case separation right there.
Only 300 H&H and 375 H&H really needed the belt because of horribly sloping shoulders.
Since this is already fired brass and we need a big stretch head spacing on the belt I don’t consider safe because I don’t know what happened on this fired brass in the past.

 

[Link]

Where’s Guffy when we need him

I remember him LOL

 

[M-61]

Where’s Guffy when we need him

Guffy’s specialty was shoulder bumping.
Although he did sell datum rings.

 

[Coyotefurharvester]

Problem with your measurement is the comparator body. It probably DOESN'T make contact in the correct location on the shoulder. You will need a few FULLY formed cases to COMPARE to the used brass you purchased to know the actual difference.

 

[Link]

I just watched some videos and where you're resizing is the distance from belt to head. Bump your die to get the right dimension - head space. This should be called belt to head [measurement;] - space.
What we know as head space in regular brass cases is irrelevant.
Right?

 

[BoydAllen]

Here is the deal, unfired brass for belted magnums reflects the reality that because there is no standard dimension from shoulder to head that brass or new ammo needs to have a lot more clearance at the shoulder to make sure that it will chamber in any rifle. In the couple of cases that I measured, the difference between new and fired was .021", which did not cause a problem because the headspace (front of belt to bolt face) was correct. The cases just blow forward and life goes on....IF you set your die just like you would for a rimless case. In most cases this means setting it for no bump and testing for fit in the rifle, since few loads produce brass that is tight at the shoulder from one firing. What you have is brass from a rifle that had a smaller dimension from head to shoulder than yours does. Both are probably correctly headspaced.

Back in the day, before knowledge of how this works was common, and the tools that we now can buy to measure shoulder to head dimensions were available, I knew fellows who had belted magnums who made the mistake of following the common instructions to screw their FL down to the shell holder, lower the ram, turn it additional eighth to quarter turn and lock it down. They would loose cases from longitudinal splits in the body after three or four firings. Everyone chalked this up to "magnum pressures". What was really happening was that with their dies set that way, they were pushing shoulders back to new brass dimension, and the brass could not handle the repeated extreme stretching. Once is no problem.

 

[Link]

A local gunsmith told me to headspace a fireformed round [in my rifle] just as you would a bench rest non belted case . Make sense? If so why not? If they chamber ok with the firing spring removed, your good to go. I cant understand why we would want .021'' [when I bump the die] of what I understand as headspace.

 

[Coyotefurharvester]

You don't want/need 0.021 shoulder/chamber clearance. So size fired brass to FIT your chamber correctly. Try your brass, with standard load development procedures. If fired brass chambers correctly WITHOUT sizing don't move the shoulder at all. If you have brass failure during load workup, toss it all, shouldn't have to even explain that. Your comparator cannot/is not giving you a real or accurate measurement. You need to set your sizing die for YOUR rifles chamber.

 

[M-61]

If fired brass chambers correctly WITHOUT sizing don't move the shoulder at all.

Yes

 

[Outwest]

How do you not move the shoulder with FL dies?

 

[William Vogel]

How do you not move the shoulder with FL dies?

Adjust the die in the press with the lock nut until you get no shoulder bump. I bump 0.001 inch but that’s me. Don’t set the die to cam over.

 

[gunsandgunsmithing]

Shoot it once and then forget it has a belt. Bump the shoulders .002-.003. Done.

 

[bsekf]

No sure at what point the action won't close on a round, but would think .020 is pretty close. Head space is arbitrary, on my Contenders and Encores I try to hold .001-.002 and every one is different because of the gap between barrel and breech. As already said the datum line is imaginary. If your headspace is too long the action won't close, too short and you will get case separation, if they fire.