Stumped 308 headspace issue

[po18guy]

+1 on the chamber cast. Mil spec brass is thicker than commercial. Softer as well. It will expand, but may not contract back (as much) from the chamber walls. It is meant to shoot and let lie. Thus inside neck expansion my leave excess neck diameter outside. Do you have an outside neck turner?
Check rim thickness, as you may have a lot of max spec rims. There are haters, but you could get some Federal match brass for your match chamber. Try a small base sizer for first loading and go from there.

 

[micj83]

+1 on the chamber cast. Mil spec brass is thicker than commercial. Softer as well. It will expand, but may not contract back (as much) from the chamber walls. It is meant to shoot and let lie. Thus inside neck expansion my leave excess neck diameter outside. Do you have an outside neck turner?
Check rim thickness, as you may have a lot of max spec rims. There are haters, but you could get some Federal match brass for your match chamber. Try a small base sizer for first loading and go from there.

Yeah as I mentioned. They are fully annealed, sized, mandrel sized for inside concentricity, then neck turned, and sorted by weight. Balling on a budget but have time to prep… I also do primer pocket uniforming, and flash hole deburring…full prep. Thanks for the input.

 

[po18guy]

I confused "neck turned with "neck trimmed.

EDIT: Do you have a Go-No go gauge? The chamber may be on the tight side of minimum in some dimension.

 

[Greg S]

Couple of thoughts...

All the 7.62 NATO chambers I have loaded for were long. I mean .004-5 long over my 308 Win chambers and they are SAAMI .002-004+

Mil brass is tough. How are you establishing you neck and shoulder temp on the annealing. I've had the springback problem with 3-4 fired 223 brass before.

Smart move would have been to FL size all the brass to insure it fits the chamber with no hard chambering and fired it. Once fired in your chamber, re-anneal, turn necks with 50% removal and load.

I tried neck turning and gained nothing in a factory neck. Tight necks yes, hence the 50 % removal for any highs.