I don't make my own, but I did buy 4 boxes each of Winchester Super X ammo.
.270 Win 130 Grain = 80 shots
.300 WSM 180 Grain = 80 shots
I'm going to sight-in both rifles using a front rest and sandbags provided by the range, and then set the remaining ammo aside, with a note that to myself indicating they were the same lot as the ammo used to sight-in and a date of purchase. That way, I figure I'll have a good chance of being accurate when I really need to be, not taking any chances.
Hope that works out for me. Lesson learned.