Headspacing question.

[Ruger44mag]

Howdy all!

I have a question about headspacing. It will probably sound stupid to yall but please bear with me :banghead: I was reading through one of my load manuals and found this written several times when talking about belted magnums. "We recommend that you set your loading dies so that the case headspaces on the shoulder not the belt". I'm not sure I fully understand about headspacing a case. Could someone please explain. Thanks!

 

[savanahsdad]

headspace is the gap in-between the bolt face and the case head, less gap the better, , if you push the front shoulder back every time you reload the case you will over work the case and shorten the case life , you should size your case so the bolt closes with little effort ,

 

[Jim Watson]

Strictly speaking headspace is the space between the head of the cartridge and the bolt face.

But gunzine and gunboard speak has gotten it to be taken as the distance between the bolt face and the cartridge stop point.
On a belted magnum, that is the facet in the chamber where the belt stops, just like a rimmed cartridge.
On a conventional rimless round, it is the shoulder of the chamber where the shoulder of the bottleneck cartridge stops.

What the book is telling you to do is to adjust the sizing die so that it treats the belted cartridge like a non-belted bottleneck. Size just enough so that the round chambers freely as the cartridge shoulder nears the chamber shoulder.

 

[Ruger44mag]

Strictly speaking headspace is the space between the head of the cartridge and the bolt face.

But gunzine and gunboard speak has gotten it to be taken as the distance between the bolt face and the cartridge stop point.
On a belted magnum, that is the facet in the chamber where the belt stops, just like a rimmed cartridge.
On a conventional rimless round, it is the shoulder of the chamber where the shoulder of the bottleneck cartridge stops.

What the book is telling you to do is to adjust the sizing die so that it treats the belted cartridge like a non-belted bottleneck. Size just enough so that the round chambers freely as the cartridge shoulder nears the chamber shoulder.

So are you saying not to size the whole case but just the shoulder?

 

[Walkalong]

No, he is saying to adjust your sizer to push the shoulder back no more than needed to chamber when you full length size your brass. This way it head spaces off the shoulder like a .308 or .30-06, instead of head spacing off the belt, which will limit brass stretching just above the case head, increasing brass life.

 

[Ruger44mag]

Thanks guys I understand now. Im loading up brass for my 375 h&h and they have been full length resized twice now so I guess I should adjust what Im doing.

 

[JimKirk]

The 375 H&H has so little shoulder that the belt almost has to be used for it ... you can try ...

 

[rcmodel]

they have been full length resized twice now so I guess I should adjust what Im doing.

At this point?
It may or may not be too late for that belted brass.

You need to bend a paper-clip or a wire into an L-shape 'feeler' and reach down inside each case and feel for a stretch ring about 1/2" to 3/4" in front of the case head.

That is over-stretched brass.
And that is where it will soon crack and break when fired.

See this most excellent illustration of case stretch & incipient case head separation from Walkalong!

http://www.thehighroad.org/showpost.php?p=6490262&postcount=8

rc

 

[Bad Flynch]

Chamber headspace is that dimension between the face of the breech and the surface of the chamber that stops the forward movement of the cartridge.

Cartridge headspace is that dimesnion from the head of the cartridge to the place forward of that which stops the forward movement of the cartridge in the chamber.

In a belted cartridge it is from the head to the forward edge of the belt.

However: many belted magnum cartridges have a false "dual-headspace" situation created by the distance from the head to the shoulder. Manufacturers, knowing that the safety dimension is the belt, often play fast and loose with the head-to-shoulder dimension. Reloaders, therefore, sometimes can have a chamber that is long in this dimension and a reloading die that is short in this dimension. The result is overworking the brass and premature case failure. This can be reversed, too (I have seen that). The result is that cases fail by head separation, which is, at best, a nuisance.

Since standard reloading dies do not touch the belt dimension, by all means set them to keep only a little clearance in the head-to-shoulder dimension. It will give good results.