I did the Apex hard sear and the Apex USB (ultimate striker block) and oh man, what a difference. Lightened the trigger pull by at least 2lbs and the reset is incredible, much better IMHO than my Glocks. Both parts made an instant difference in the smoothness and over-travel of the trigger but after 200 rounds with the new parts it is even better. The lighter trigger is silky smooth but not too light, has a very even pull and very crisp break, and the reset is short and very positive. Rapid fire follow up shots are a breeze and it made a very accurate pistol even more so enjoyable to shoot. After I did my shield, I upgraded by M&P compact .40 and full size .40 to the Apex sear and USB as well and all feel exactly the same to me. What an improvement all the way around.

And for anyone who doesn't know, the standard Apex Hard sear and USB kits fit both the shields plus the compact and full size 9, 40, and 357 sig. Apex has different parts for the .45s and pro series.