Quote:
Originally Posted by jbouwens
I deprime, sort out non brass, throw them in the tumbler for 4 hours, dump them out onto a towel and roll them around a bit, let them dry for 3 hours, inspect for pins in the flash holes (1 to 2 % will have an issue with stuck pins), throw them into my vibrating tumbler with corn cob media laced with Nu Finish for 15 minutes to put a protecting layer on them to keep them from tarishing (stainless pin method gets them so clean they will tarish just by looking at them swear... I think the pins open the pores in the metel like sandblasted metal).
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Actually, what the stainless steel pins are doing is increasing the surface area of the cartridge.
I would not tumble brass for 4 hours with stainless steel pins.
The trick to long life of any metal is to minimize the surface area.
Increasing the surface area by any technique (sand blasting, whatever) weakens the metal.
The case is much more susceptible to cracking.
Forget the stainless steel pin tumbling if cartridge life is a concern.
Those chemicals that are shining the brass is also a concern.
If you find the wrong concoction, the chemical will attack the grain boundaries, again weakening the cartridge.
Just my humble metallurgical opinion.
