100's
100 primers in a tray,
100 bullets in a box,
therefore, 100 is a good size for plastic ammo boxes (rifle and pistol).
Yes, I do batches up to dropping powder. All these steps can be done with the TV on. Then I have boxes of 100 primed cases ready to go, and I concentrate on working up through the powders loading range. At my range some people mount a powder measure to their shooting bench. I may try that soon, and it will be handy to have primed cases ready to go.
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