Just wanted to post a quick follow-up. After talking with Adam, the customer service guy at TulAmmo, I decided to take another trip to the range and document all of the FTF's and FTE's.
After sorting through all 1300 rounds (not 1200, as I first thought), I have what appears to be 8 or 9 different lot numbers. I had 8 boxes left (we shot two boxes) of one of the lots numbers from the first trip to the range, and none (we shot the only box) of the other lot number.
For the second range trip, we took two boxes of one of the same lot numbers as the first trip, and one other random box because we didn't have any more of the second lot number.
We shot the ammo through the same Glocks and magazines as the first trip, and also included a M&P 9 Shield with two magazines.
In the end, it turned out to be a complete waste of time and ammo, as we could not replicate the first range trip. There wasn't a single malfunction. :shrug:
The only difference between the first and second range trips was the fact that we didn't have anymore of one of the lot numbers. We shot the only 50-round box during the first trip. I was pretty confident that the FTF/FTE rate was between 50%-75%, but it's beginning to look like it could have been slightly less. I really hope it was just one problematic box.