Originally Posted by
DBZ220
I got my information from a S&W LE rep, and some pretty good sources on other forums. Seems October of 2010 S&W improved the sear return spring and detent, and some other small tweaks, across the M&P line. The triggers on my current M&Ps are worlds better than previous. The reset still isn't as distinct as on a Glock for example, but much better than original.
These improvements also are supposed to help eliminate the sporadic dead trigger issues some high volume users have reported with their M&P pistols.
A base line to go from is the spent shell casing. My current M&Ps all have fired casings dated from June and July. My wife's are the same. The M&Ps to be avoided, in general, are ones that DO NOT have the stepped rear sight, or serial numbers in the MPxxxxxx range, these being earlier models, more prone to rust issues, mag drop issues, gritty triggers, etc, etc, if they haven't gone back for service. Again, this is what I've gathered from a variety of sources prior to switching back to the M&P platform for EDC. Our 5 M&Ps here are all in the DYxxxxx serial range and are excellent performers.