Fire Forming Question

[Clodo Ferreira]

Hi NM,
To me, what I do with some NORMA 7x57 cases a little shorter in headspace for my M1935 Mauser european CIP barrel, the best way is to do this, the same as Wyatt Smith describes:
"If you want to minimize stretching I would size them up to a larger caliber (338 maybe) the size them back to 30 until you get a crush fit when closing the bolt. This will keep the case head against the bolt when firing.
I doubt the load will be any different with the ff and non ff cases as the case will meet the chamber before full pressure."
In my case I run the 7mm cases throught a .30" expander button and run then in the 7x57 sizing die leaving a small part of the neck at 30" to get that light crush fit. Done! And load that cases with my usual hunting loads. Period.

Good luck!

CF

 

[Nevada Mike]

Hi NM,
To me, what I do with some NORMA 7x57 cases a little shorter in headspace for my M1935 Mauser european CIP barrel, the best way is to do this, the same as Wyatt Smith describes:
"If you want to minimize stretching I would size them up to a larger caliber (338 maybe) the size them back to 30 until you get a crush fit when closing the bolt. This will keep the case head against the bolt when firing.
I doubt the load will be any different with the ff and non ff cases as the case will meet the chamber before full pressure."
In my case I run the 7mm cases throught a .30" expander button and run then in the 7x57 sizing die leaving a small part of the neck at 30" to get that light crush fit. Done! And load that cases with my usual hunting loads. Period.

Good luck!

CF

I understand what you are saying, but with a belted cartridge won't the BELT keep the case head against the bolt face?

 

[Clodo Ferreira]

Hi NM,

Not necessarily. That's because the usual great tolerances between the chamber belt stop and the actual case belt width. And the greater ones between the bolt head and the chamber lenght to the shoulder! So, is much better to treat the belted cases as normal rimless ones in a gun with too large chamber headspace.
Good luck!

CF

 

[Nevada Mike]

Hi NM,

Not necessarily. That's because the usual great tolerances between the chamber belt stop and the actual case belt width. And the greater ones between the bolt head and the chamber lenght to the shoulder! So, is much better to treat the belted cases as normal rimless ones in a gun with too large chamber headspace.
Good luck!

CF

Exactly what I am planniing to do!

 

[Bob Nelson 35Whelen]

I have several hundred new 308 Norma Magnum brass. The factory shoulder on new brass is about .021" shorter than my fire formed rounds I have. So I need to FF ALL my brass to a consistent length for loading. Is there any way to properly FF brass without incurring several hundred rounds of barrel wear on my new Brux barrel? I have heard some people use Cream O' Wheat, but never tried it and no idea exactly how it works.

Thanks.

@Nevada Mike
You don't need to fire form before use and waste powder or projectiles.
Just expand the neck to .338 or 358 then resize the case so it's a slight crush fit in the chamber.
This method puts a false shoulder in the case ande eliminates the headspace issues
Bob

 

[Bob Nelson 35Whelen]

If you want to minimize stretching I would size them up to a larger caliber (338 maybe) the size them back to 30 until you get a crush fit when closing the bolt. This will keep the case head against the bolt when firing.
I doubt the load will be any different with the ff and non ff cases as the case will meet the chamber before full pressure.

@Wyatt Smith
You have learnt much young grasshopper.
I have just started reading this post and gave the same answer.
Great minds think alike.
Bob

 

[Bob Nelson 35Whelen]

Hi NM,
To me, what I do with some NORMA 7x57 cases a little shorter in headspace for my M1935 Mauser european CIP barrel, the best way is to do this, the same as Wyatt Smith describes:
"If you want to minimize stretching I would size them up to a larger caliber (338 maybe) the size them back to 30 until you get a crush fit when closing the bolt. This will keep the case head against the bolt when firing.
I doubt the load will be any different with the ff and non ff cases as the case will meet the chamber before full pressure."
In my case I run the 7mm cases throught a .30" expander button and run then in the 7x57 sizing die leaving a small part of the neck at 30" to get that light crush fit. Done! And load that cases with my usual hunting loads. Period.

Good luck!

CF

@Clodo Ferreira
Another smart man.
That's what I do as well.
I do it when forming K Hornet sases out of 22 Hornet cases.
I neck them up to 7mm the fls. This puts a false shoulder on them and they look almost like a fire formed cases. Since doing that my attrition rate of split cases went from 30% to virtually zero
Bob

 

[rdog]

I have several hundred new 308 Norma Magnum brass. The factory shoulder on new brass is about .021" shorter than my fire formed rounds I have. So I need to FF ALL my brass to a consistent length for loading. Is there any way to properly FF brass without incurring several hundred rounds of barrel wear on my new Brux barrel? I have heard some people use Cream O' Wheat, but never tried it and no idea exactly how it works.

Thanks.

The old 308 Norma is a belted case that head spaces off the belt , just fire them as normal hunting ammo & they will blow the shoulder foreword & adjust the sizing die to not set the shoulder back when reloading them, you will achieve little by blowing the shoulder foreword with reduced loads.

 

[Clodo Ferreira]

Hi rdog,

That's right, in theory. But, rarely, they work because the usual "great tolerances between the chamber belt stop and the actual case belt width. And the greater ones between the bolt head and the chamber lenght to the shoulder!" Combined, they create an excessive headspace. "So, is much better to treat the belted cases as normal rimless ones in a gun with too large chamber headspace."

CF

 

[Clodo Ferreira]

Hi rdog,

That's right, in theory. But rarely they work because the usual "great tolerances between the chamber belt stop and the actual case belt width. And the greater ones between the bolt head and the chamber lenght to the shoulder!" Combined, they create an excesive headspace so a separation ring near the belt after the first shot is not rare. Then "is much better to treat the belted cases as normal rimless ones in a gun with too large chamber headspace."

 

[Clodo Ferreira]

Sorry by the double post!!