I have consecutive serial number NMV 38's. At my very first every CAS match the mentor who walked me though loading table, stages, and unloading table told me to always holster the same gun each time in your left and right holster for the purpose of keeping a routine going at the loading table. The gentleman has been shooting for a long time, has won matches at the state level, and that seemed like good advice at the time. So my pistol with the serial number ending in 5 goes in my left holster and serial number 6 goes in my right. I even place them on the table, 5 below 6, with five going into my left holster first followed by 6 in the right. I don't think I could tell the difference in them if I was to mix them up, however that routine has stuck with me. Probably being way to OCD about it, but it hasn't hurt anything so why change now.