cheap without surplus, accurate to 100 yards and able to kill varmints... I would say that either 223 or 9mm would handle these tasks very well. the 9mm maxes out at about 125-150 yards for effective range but is much cheaper, more fun to shoot and offers longer barrel life than 223.
other than that I can't think of any others.
all guns lost in a tragic smelting accident.
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