How do you tell if necks are too thick

[clearwater]

Sized some brass from .284 to .257 for a wildcat. All the brass I inherited with the gun had been shaved with a forster tool. Some of that inherited brass cracks at the neck when resizing even after anealing.

I would like to either skip the step of shaving the brass or at least get a manual or info on how to do it
correctly.

Is there a way to tell if necks are too thick without buying a special tool or getting the chamber casted?

 

[atmoshpere]

Just to clarify: You received some 284 cal brass that had been neck turned, with a gun chambered in a 257 wildcat? And then you neck sized the brass down to 257?

If this is the case, I doubt that your necks are too thick. I don't think being too thick usually leads to cracked necks anyways, but it can give you chambering issues.

I would guess that what may be the case is that some of the original thinned 284 case neck was moved into the shoulder upon sizing, leaving a thick/thin transition on the shoulder. Are the necks cracking circumferentially around the neck/shoulder junction or vertically up/down the side of the neck?

If the necks are splitting vertically after being properly annealed I would guess that they are too thin to accomodate the stretching they undergo within your chamber.

As far as telling whether they are too thick or not without a tool? I don't know how to tell, other than to ask how thick is too thick? Do they chamber loaded and unchamber after firing without issue? If so then they are most likely no too thick for your chamber.

Maybe someone who has measured the thickness increase associated with necking down a cartridge will chime in.

Good luck, but if your necks are still splitting after being annealed, I would get some new brass so you know exactly what has been done w them.

atm

 

[clearwater]

The brass that has split necks was sized from 284 than shaved. It had been fired twice and shows
cracks when I size it right at the shoulder/neck. It appears it was shaved too thin at that point?

I have new brass that I resized to 257 from 284. Before I load it I wanted to know that the necks
were not too thick and develop high pressure upon firing. I have fired couple of rounds with starting loads and the a bullet will easily slide in and out of the unsized case.

 

[IdahoCTD]

If it will slide in and out of new fired brass that hasn't had the neck turned then it is fine. I have a .30-8mm with a .337 neck and my loaded rounds are .335. There is enough spring back on the brass that I can pop the primers out and load a bullet right back in the case until the cases get worn out and wont spring back.

 

[velvetant]

Sounds like you did the right thing with the starting loads, You should be good to go like the others said.
What is the wildcat you are working with...25-284?
That's what I have. reloads with Retumbo and a 115gr nosler bt or 120gr Nosler Partition work really well in mine

 

[rick smith]

clearwater, you answered your own question. If the bullet slips easily into a fired case, you are good to go the necks are not too thick.. If you have a good dial caliper, measure the OD of the neck of a loaded round, subtract the bullet diameter and divide by two. That will give you the neck wall thickness. Do that with your new brass and with the neck turned brass.Rick.