Greetings,
Thanks to all who provided input on the "lead-pot brass annealing" thread. The purpose of annealing is to provide longer neck and shoulder case life and more consistent neck tension. So far after 10 full power 30-06 reloads and three annealing cycles the case necks and shoulders show no pitting or cracking.
What I didn't count on is a new failure location at the lower case body, 0.5" up from the case base. I had a complete case separation and upon inspection of the other fired cases about a third of the test cases had signs of impending separation- either external grooves or bright lines all at 0.5" above the case base (see pictures).
All cases had been full length resized. Measurements of the case widths at 0.5" above the base are listed below.
1. New unfired case with FL resizing- 0.462"
2. Four times fired and FL resized- 0. 464"
3. Nine times fired and Fl resized- 0.465"
4. Ten times fired and unresized- 0.466"
5. Ten times fired and full head separation 0.466"
So it seems that despite full length resizing that the base of the case grows and once it reaches 0.465-0.466" that one gets case fatigue and failure with my particular 30-06 rifle.
It would appear that to avoid lower case body failure that I can:
1. neck-resize only (to avoid work-hardening the body)
2. just trash the cases after a set number of firings
3. measure the case widths and trash when approach 0.465"
4. do a better job of seeing the impending case failure lines
(which may be too subjective to call)
I'd be interested in other's opinions if possible.
best wishes- oldandslow