Into lands or false shoulder to fire form belted brass

[Gwine]

I do set my headspace ~.002 off the shoulder on my fired brass, but have never loaded virgin brass on a belted before and the slop at the shoulder bothers me.

I think I will take 20 pieces and put a shoulder on half of them, do my load development and see if I notice a difference between the 2 batches. If I don't see a difference then I will just load and shoot the rest.

 

[Dean2]

I do set my headspace ~.002 off the shoulder on my fired brass, but have never loaded virgin brass on a belted before and the slop at the shoulder bothers me.

I think I will take 20 pieces and put a shoulder on half of them, do my load development and see if I notice a difference between the 2 batches. If I don't see a difference then I will just load and shoot the rest.

Have done it more than once . Even sectioned the different versions. Based on what I saw, there will be no difference between the false shoulder ones and those u headspaced off the belts.

 

[jarnold37]

I am getting ready to start load development with some new brass in my 7RM. This will be the first time I have started with new brass in a belted mag.

In order to prevent excess stretch in the new brass I plan on one of the above to hold the base of the cartridge against the bolt face. I have seated the bullet into the lands on some standard cartridges for this purpose before, but am thinking about the shoulder so that I can experiment with seating depths while fire forming.

If you have a preference, can you elaborate.

If the shoulder is the way to go, what is your method. I grasp the idea, but would like to here your practices.

Thanks in advance. I appreciate the knowledge available here.

Well, you could turn off the belt in a lathe, which I have thought about doing many times, or choose a non-belted cartridge to start with which I have done in latter years.

 

[gohring3006]

Well, you could turn off the belt in a lathe, which I have thought about doing many times, or choose a non-belted cartridge to start with which I have done in latter years.

I curious why you believe leaving a unsupported part of the case in the chamber is a good idea?

 

[bigngreen]

With a belted case the brass is held in the same position as it will be if you jamb a bullet or create a false shoulder, it's not going anywhere. In a non belted case it does shove the case forward and then it expands to the chamber then is shoved back stretching the case at the case head. If you need to jamb a bullet to fire form a belted mag because of head space you need to see a gunsmith or get the gun fixed because it headspaces on the belt.

 

[25WSM]

The problem on belted mags is not when you fire the first time new brass. It's how much setback you get when you set up your dies. Do it by the instructions and you will almost always create too much headspace/setback. Use a comparitor and set back .001 to .003 and lock it down and your good to go. Seems to me belted mag dies are always setting back too far compared to beltless dies. Belted mags will always have the belt to headspace on so even if you crush .050 it probably would still fire unlike a beltless. But case head separation will get you quick.
Shep

 

[Rich Coyle]

Well, you could turn off the belt in a lathe, which I have thought about doing many times, or choose a non-belted cartridge to start with which I have done in latter years.

Turning the belt off can work. Here are three cases. The first is a 9.3X64 Brenneke, the next is a Norma 7 Rem Mag with the belt turned off to match the 9.3 case and the third is a hydroformed case with headspace already correct for the chamber.

 

[nicholasjohn]

You could measure the length to the shoulder on your unfired brass with a comparator, and see how far it's being pushed forward on the first firing when you just put one in the chamber and shoot it in the standard fashion. ( That is, headspacing on the belt, as intended.) If the difference is large, putting the secondary shoulder in there for headspacing may be a good idea. I'm guessing though, that the difference will not be very large. If you sacrifice a fired case and section it, like somebody suggested in this thread, you'll be able to see how much stretch there was just ahead of the web. If it got pretty thin on one firing, you will have your answer.

Another thing to keep in mind is that if you do decide to use the secondary shoulder method, the extra sizing of necking the case up and hten back down to establish that shoulder is going to work-harden your bass as much as an addition firing & sizing would have. You'll need to figure that into your annealing program, if you do anneal your brass.

As expensive as good brass is, I can see why you have this concern. I'm interested in seeing how this turns out for you. I have had the same thoughts about this as you have. Keep us posted on how this one goes for you.

 

[25WSM]

Really no need to get rid of the belt just don't use it. If I'm not mistaken but Probally am on this. I'm not old enough to remember this but I think the belt on the h and h was made to take the headspace because the 375 didn't have much shoulder and it was a dangerous game cartridge so needed it to be dead nuts reliable. But now when people started making real shoulders on that brass the shoulder was reliable to headspace from but the belt was already on the brass. I've never found a problem having a belt on the brass. I do think factory specs of belt headspace are more lax than a true headspace which is why I don't use the belt.
Shep

 

[bigedp51]

7mm rem mag headspace
https://www.longrangehunting.com/threads/7mm-rem-mag-headspace.85163/

Below shows the variations in belt thickness and headspace, and if I remember correctly someone here stated that the average belted rifle has about .004 head clearance. And this can vary on the cases belt plus and minus manufacturing tolerances.

And as a side note, I have had new .243 Winchester cases as much as .009 shorter than chamber headspace.

Below are .308 cases fired in a brand new Savage rifle and full length resized until they failed. Look at the bottom chart and note that these cases did not start to stretch until after the 6th firing.

 

[longrange240]

you have the belt, blast away.

This

 

[Rich Coyle]

longrange240 wrapped up this thread.

 

[Andrew Cowling]

I am getting ready to start load development with some new brass in my 7RM. This will be the first time I have started with new brass in a belted mag.

In order to prevent excess stretch in the new brass I plan on one of the above to hold the base of the cartridge against the bolt face. I have seated the bullet into the lands on some standard cartridges for this purpose before, but am thinking about the shoulder so that I can experiment with seating depths while fire forming.

If you have a preference, can you elaborate.

If the shoulder is the way to go, what is your method. I grasp the idea, but would like to here your practices.

Thanks in advance. I appreciate the knowledge available here.

Neither is required. Just use a smeer of sizing lube on the case in the chamber. It will allow the case to set back against the bolt and blow the shoulder forward.

 

[Dean2]

Neither is required. Just use a smeer of sizing lube on the case in the chamber. It will allow the case to set back against the bolt and blow the shoulder forward.

This is REALLY bad advice if you are using full power loads. Someone put this on the net a few years ago for fire forming with light loads and cream of wheat but it keeps getting repeated without that caveat.
DO NOT do this with full power loads. Cases will fire form all on there own. You want the cartridge to properly grip all portions of the chamber as it stretches. This also gives u the very best fit of case to chamber without placing excessive pressure and thrust on the bolt face.