Lesson learned -

[Jeff Porter]

I was setting up iron sights in my 6 BRA right after a thorough cleaning. First two shots had hard bolt lift and evidence of some solvent still in the neck of the chamber …

Then I find this when annealing. Swab it dry patch before shooting

 

[BRGUY]

Work hardened brass?

 

[rwj]

Agreed that a dry chamber is a good thing and lack thereof can cause high bolt thrust. But how would that cause a split neck?

 

[Jeff Porter]

Over pressure

 

[rwj]

Over pressure

The case neck can only expand radially until it contacts the chamber wall. This is the maximum strain (stretch) that can be applied to the neck regardless of internal pressure.

 

[Jeff Porter]

With the non compressible fluid in the chamber the pressure is at that location.

 

[Bill K]

Not to start a argument, but I think the pressure spike will be from the shoulder back to the base, not into the neck. I would say more annealy those cases.
From the photo it appears that they have not been.

 

[rwj]

With the non compressible fluid in the chamber the pressure is at that location.

Pressure acts uniformly on all surfaces…

 

[Jeff Porter]

Not to start a argument, but I think the pressure spike will be from the shoulder back to the base, not into the neck. I would say more annealy those cases.
From the photo it appears that they have not been.

Amp annealed every reload. Has been decapped and washed and discovered while annealing.

 

[Jeff Porter]

5x fired to answer your next question, 28.9 H4895 with a 105 Berger at 2900 to answer the one after that. And .272” no turn neck for your third.

 

[Capt. Oblivious]

Do you turn necks?

 

[Kracken McGraw]

I was setting up iron sights in my 6 BRA right after a thorough cleaning. First two shots had hard bolt lift and evidence of some solvent still in the neck of the chamber …

Then I find this when annealing. Swab it dry patch before shooting


View attachment 1593351

I appreciate the advice.
I think it will remind me after cleaning chamber with a shotgun patch on the swab, to run another dry patch down the barrel.