I just acquired a full sized .40 2nd hand. The gun is Serial numbered MPA52**. I have gathered that the newer models have a dished out area on the breachface and a differant striker. Has anyone here needed to send theirs in to be upgraded or should I keep it as is? The inside of the dust cover is blank, no Rev N or anything there at all. I fired about 80 rounds through right after I got it with no issues except the rear sight was off, which I have since fixed.