The least I'll load is 10, for local big game hunting (which is mostly what I do anymore). Will load 50 if going on a trip.
Have only loaded 20 even for trips to Alaska or Africa, depending on how much that rifle will be used. It also depends whether I bring more than one rifle, and the length of the hunt. Brought 100 7x57s to Africa on a month-long "cull" safari, along with 50 9.3x62s.
For "colony varmint" cartridges at least 200 and sometimes 1000--depending on how many rifles are going, and for how long.
