I just purchased a new Zero Tolerance 0551 the other day and noticed a few differences between my example and any others I have seen. My S/N is in the 1500's which also dosent make sense but I found out that not all of the 1000 made it past QC. My 0551 has the improvements made to the 0550 like the chamfered edges and changes in the jimping but also has a thin lockbar cut on the vertical portion, horizontal is the same as 0550. I don't have any pics but it is just like the cut on the Kershaw Tilt. Did this come out as an improvement that I am not aware of or am I missing somthing. Thank you for any and all help.