There you go. May as well call them different headstamps and sort by year. Even with the same year, they could be from differing lots and be different. I'd sort by year and then weigh them, culling the wacked out weights. And trim them first to give some chance at uniformity.
"Always place your clothes and weapons where you can find them in the dark"
"Understand that the enemy is not the enemy in his own eyes ;this may offer you an opportunity to make him your friend. If not, you can kill him without hate, and quickly."