I got a M&P 40 police trade from buds the other week.  Shoots well enough, but it has the old crap trigger.  My M&P9 had the newer trigger, and it was OK.  I upgraded that to the apex kit with poly trigger and wow it is awesome.  So I got the same kit for my 40.  During the install, I couldn't swap out the sear spring as the older sear block had a way smaller hole.  So I must left the old spring and cap in.  After finishing, the trigger pull  is nice but the reset is hardly noticeable.  I'm guessing this is from either something in the old style rear sear block, or maybe its just that spring I couldn't swap out?  Wondering if anyone might know.  If I need to buy the newer sear block I will.  But in some video I watched the guy mentions apex will send a different spring?  Although aside from noting there is a difference in the springs and sizes, he mentioned sear fluttler as a negative outcome and nothing about the reset.

Further I have isolated it to the lower as swapping complete slides from my good m&p9 to the 40 will continue reproducing the issue on the 40 lower with the older sear.

I'd suggest you get the new, large-sping sear block anyway for reliability. If you are willing to send the gun to S&W they should change it out for you at no charge if you complain of"sear flutter" (but pull all the Apex parts first or they will remove them). Alternatively you can buy a new sear block from Midway for about $30. If you decide to stick with the original small-spring sear block, call Apex and they should be able to send you the correct spring. If not, send me an IM as I should have one spare somewhere.

As for the reset, you need an Apex RAM. Also useful so the gun can still be made to shoot if the trigger spring breaks.

pretty sure that apex says you MUST swap out the sear block, otherwise the trigger is in a dangerous condition

OK thanks all. Will get it fixed.  Calling apex and will ask them.

In regards to the apex Ram.  My 9mm doesn't have the ram kit and the reset is great.  Nice audible and tactile reset.  The 40 you can barely hear and feel the reset.

The reset issue has nothing to do with the sear block, well very little at least. The tactile reset on the M&P comes from the force at which the trigger loop falls back under the sear. To increase that tension S&W has increased the bump on the right side of the slide stop forcing the trigger bar more toward the sear. The same result can be had by simply bending the trigger bar a little towards the sear. You want to bend it to the rear of the double 90 degree as you still want the slide stop to provide all the force on the bar that you can get.

I bought a NIB M&P Pro 9mm this past Saturday, Fired Cartridge collection date 10/22/2013 I see it has the new 1:10 Twist Barrel but was suprised to see it has the old style Sear Block and Slide Lock. Reset was actually a little better than My older M&P Pro I had a few Years ago, it had NO Audible Reset! But not as good as My M&P Full Sze 9mm with was made in June of 2014
Having already done the Burwell Trigger Job on My Full Size I worked on the Sear on the Pro and made the Trigger Pull even better than the Factory Trigger Pull and the Reset got Better and a lot Shorter but it doesn't have a Audible click quite as loud as My Full Size M&P which is almost as loud as My Sons G17

I have read that the new sear Block is better than the old one, I found them on Midway and a couple of other sites for about 40.00 I have also read that it may not fit some Pistols, Can Anyone tell Me how to check for that? I plan to get the new Slide Stop with the Hump on it, it's only 15.00 and is suppose to help the Reset.

Would changing just the Slide Stop be enough or would Y'all recommend changing the Sear Block too? What about adding the Apex Ram? If I upgrade to the New Slide Stop is that going to be enough or should I go ahead and add the Ram as well? I rather order all the Parts Once rather than 1 at a time to see what helps.

I am happy with the Trigger Pull on the Pro after I worked on the Sear and polished it, but the reset could stand to be a little more Audible than it is now.

Thanks

New sear block with the right springs, new slide stop and new trigger bar will give you all the reset you could want.

This.  

You need a new sear block to prevent a dead trigger, not to increase tactile reset.  Bend the trigger bar and you will get the reset you want.

Did, you try the Apex RAM?  I have this installed in my Older .40 M&P.  The reset is very noticeable.