1st batch = composite endcap and black knob
2nd batch = normal endcap and grey knob
red knobs mean non returnable.
The sure way to tell is the composite end cap. Most of them have black knobs, but there were some late production ones that had the grey knob. Also, most of them had the blue paint extend further down the handle, There were some repaired endcaps on some 1st batches that had a rubber end cap inserted. If it has a plastic target endcap, then it is definitely a second batch. Although the 2nd Batch's were and are a great performing stick, they can't compare to the 1st Batch. In my opinion, one of the hottest stick's ever made.
Also, the very early 1st Batch's did not have the "NSA Approved" stamp on them. I have found that the one's without the stamp are even hotter right out of the wrapper than the one's with, although the one's with the stamp catch up very quickly