Fireforming Brass Loss/Failure

[bozo699]

New brass for any kind of reforming. You could get some hornady 6mm rem brass new. Its usually available, or find the holy grail- 7x57 rws brass. Once brass is fired it hardens up and cracks when forming.

I love my RWS Brass!.....
Wayne

 

[pintopete]

Depends on the book...

 

[Homerange]

Depends on the book...View attachment 1241658

Still for FF'ing you're way too hot. Case volumetric efficiency isn't even formed therefore starting loads would be more appropriate.

 

[pintopete]

So, I will either find new or anneal the brass I have, and if I am understanding all these suggestions, use a starting load with a fast powder? Some say heavy bullet, others light. I had thought heavy was correct, and to seat the bullet to jam to ensure the case base remains against the bolt face.

Seems like the lack of malleability or brittleness of the brass is the bigger issue.

New 257 Roberts brass is not easy to come by. I think I have a line on some through a forum member.

found this too...

Reloading 101: Fireforming Cases

Written by Sierra Bullets Ballistic Technician Duane Siercks What is fireforming? Fireforming is the process of creating custom fitting cartridge cases for your specific firearm. Having the “…

sierrabullets.wordpress.com

Thanks, Peter.

 

[bozo699]

Pe

So, I will either find new or anneal the brass I have, and if I am understanding all these suggestions, use a starting load with a fast powder? Some say heavy bullet, others light. I had thought heavy was correct, and to seat the bullet to jam to ensure the case base remains against the bolt face.

Seems like the lack of malleability or brittleness of the brass is the bigger issue.

New 257 Roberts brass is not easy to come by. I think I have a line on some through a forum member.

found this too...

Reloading 101: Fireforming Cases

Written by Sierra Bullets Ballistic Technician Duane Siercks What is fireforming? Fireforming is the process of creating custom fitting cartridge cases for your specific firearm. Having the “…

sierrabullets.wordpress.com

Thanks, Peter.

Peter,
P.O Ackley designed the improved case so you don’t need to jam it is supported at the shoulder datum. When ff you can’t use ackley load data you have to use the .257 load data after you ff then use ackley data. There usually extremely accurate so I have fun shooting and don’t waste time ff first. Now something like the Dasher or 6brx you need a false shoulder or jam bullets but not the ackley. Good luck. Also unless the cases you have been fired multiple times you should be able to ff them without the issues you are having with a little less powder although if you could anneal it will help. I have ff 6brx from 6 times fired 6br brass with no issues and your blowing the shoulder forward. .100

Wayne

 

[std7mag]

For forming 257 Roberts AI, i'm starting off with PPU 7X57 Mauser brass. Cost effective from Grafs.
Run through 257 Roberts full length sizer.
Trim, as sizing down will lengthen it.
Anneal.
Load whatever bullet you have with at least a middle powder charge out of a load manual for whatever bullet/powder combination your using.
Case removed from chamber will be AI.
Do not jam the bullet into the rifling, as this will unnecessarily increase your presures.
Ackley Improved chambers, when headspaced correctly, will have a slight interference at the neck/shoulder junction of the case.
Hence why when setting headspace an AI chamber, the standard cartridge no-go gauge is now your go gauge.

 

[JSH]

Wayne totally agree, P.O designed it that way but some folks have changed that to what they thought was better.

The OP will find there are various ways to skin a cat, each cat is different however. I still use cerosafe on wildcats I don’t have a reamer print for.
You may want to neck up to .264, then back down to get your brass to stay against the bolt face, aka false shoulder.

 

[Ackman]

You don't know how many times that brass was fired or in what kind of chamber. Looks like the necks are brittle from being very-very worked and sized way down many times. I know .257 brass is hard to find and you'd like to use what you've got, but don't, toss the stuff. As people have suggested, there are other ways to get/make .257 brass. And fireforming, load with whatever bullet/powder you plan to use and find your load as with any other cartridge. Very simple. My fireforming loads are all at least book max for the standard cartridge....remember, they're being shot in a much larger chamber so backing off is not the way to go..

 

[watersfam]

Is the brass new?
If you have new brass, and the chamber is done correctly, you should have nearly zero failures. If the brass isn’t new, I’d either replace it, or anneal it.

What if cartridges are unused, old stock, factory loads?

 

[Ccrider]

Anneal

This will help. Back the load down as suggested. I neck down 7mm to 257stw and shoot a really hot load. If I don’t anneal, I will sometimes get splits in the neck on the first firing.