A former exec at SureFire once told me that they don't necessarily build them in order by the SN. But each batch would be slightly different due to improvements or corrections.
So say they built 29,000 for oh I don't know, let's say the US Coast Guard it was not be unusual for the serial numbers to not be in sequence like 12004, 5, 7 but might be 22999 and 14002. But each in that batch would be alike. Now say they built another batch for I don't know, the SPCA and the order was 8000, all 8000 would likely be slightly different than the batch for the Coast Guard. If they built a batch for LA Police, that would differ some from the previous two.
He said often the change would only be known by SureFire like changing a rubber compound for the o'rings or a different supplier for the boot cover, but sometimes the changes could easily be seen such as in the logo.
It's surprising the light that was the topic of this thread was not rejected. At one point they had QC checks of 100%. Perhaps now that they are more consumer oriented than military they have changed that.