[Pay Dirt]

I was not so curious as to what actual numbers appear but why they weren't serialized to a gun. Thus far I've heard two plausible explanations.
1) Left and right extractors were produced as a set, and numbered so, then thrown in a bin well before they were fitted to a barrel yet now (then) existed as a set.
2) Left and right extractors were fitted to a barrel and assigned the same production number as say the barrel before the barrel was fitted and then serialized to a specific receiver.