M&P 45 Trigger Problem

[S500N]

I sent my full size M&P 45 to the S&W Performance Center for the M&P Pistol Action Package as well as to install a Massachusetts trigger bar and Massachusetts trigger bar spring. I received the pistol back late yesterday. Prior to sending the pistol away, I had just under 600 rounds of 230 grain ball through the gun without any malfunctions. I took the gun to the range today. I fired 100 rounds of 230 grain FMJ through the pistol. On 17 occasions the gun would feed, fire, eject, extract, and chamber a fresh cartridge as normal. However, the trigger would not reset, and I was unable to fire the currently chambered cartridge. If I press checked the gun, the trigger would then reset, and I would continue firing until the magazine was empty or the next time the malfunction occurred.

Does anyone have any insight or suggestions as to the cause of this particular type of malfunction? Also, as a side note, the performance center stated that no special Massachusetts trigger bar exists for the 45 M&Ps. Is that correct?

Thanks,

Steve

[DocGKR]

Call the S&W PC first thing Monday morning, as that pistol likely needs to go right back...

[beastfrog]

However, the trigger would not reset, and I was unable to fire the currently chambered cartridge.

Trigger bar malfunctioning or sear spring not installed correctly.