Pin Punches, What Kind

Roll pin punches are good for roll pins. Regular punches for regular pins. Steel. Watch the Apex videos. Prepare for lots of swearing trying to get the trigger spring back in. Don't remove the rear sight

Ask me how I know

Here's a long winded reply.
The M&P series retaining pins for the Locking Block Housing up front and the Sear Block Housing in the rear are different styles depending on the "Series" of M&P. The M1.0 series have
9/64" coiled roll pins; the M2.0 series (latest generation) have 1/8" solid pins. A screwed up looking roll pin end is just as unsightly as a burred screw slot from not taking the care to
use a proper fitted punch for the task. The roll pins will be tight on the M1.0 series that have not been disassembled before, therefore using a 1/8" short shaft starter roll pin punch to get the pin
moving will prevent bending a longer shaft punch; finish removal with the longer shaft punch. The reverse is true for installation with the exception that employing a roll pin starter "holding" punch
prevents marring the pin ends. The retaining pins can be removed in either direction; generally I remove these left to right by convention only, however it is more efficient to remove them
right to left, as the that is the direction the trigger headed pin has to be removed, so you save flipping the frame over one time! Although the pins are symmetrical front / rear I restore them
to their original locations and even insert them / remove them by the same end, just because. Sometimes the roll pins can be hard to start back into their holes as the coil of the roll pin may have
opened up a bit, in that case you can slightly chamfer the end of the pin by turning the pin in a hand drill against 80-120 grit paper, re-blue end as desired.

The trigger headed pin I usually use a brass punch. Make sure the take down lever stays in the vertical position initially so it will not be blocking the pin from removal.

The short / long roll pin punches as well as the roll pin starter holding punches can be sourced from Brownells.

.............

Replacing the trigger spring is quite easy. The Apex kit comes with a polymer slave pin. This one here just happens to be steel. The tip is assemble the the trigger-trigger bar sub-assembly
outside of the frame ! as you can manipulate the spring loop about the slave pin much easier.stall the sub-assembly and then simply displace the slave pin with the Trigger Headed Pin. No commotion necessary.

Yes once you put the assembly back into the frame. However I found my slave pin to be worthless. YMMV

The Apex slave pin is well-intentioned its just poorly designed; the problem is their pin is tapered on both ends which allows the tensioned trigger pin to fall into the cleft
between the slave pin and the end of the trigger headed pin, which requires one to pull forward the the spring loop to allow passage of the trigger pin. The space is very limited to
perform that task without deforming the spring loop. To overcome this problem, a slave pin fabricated from the largest decimal no. drill that will fit freely thru the trigger head pin tract
is tapered on one end to easily capture the spring loop whereas the opposite end of the slave pin is precisely the same diameter as the trigger pin so there is no space for the
spring to fall into between them as the trigger pin is advanced to capture the trigger spring. The pin can be installed just as easily with the locking block in the frame as outside the frame
after you do it a few times. The occasional user, sub-assembly first is the way to go.

Nice job a5werkes. If I ever wanted to change my M&P, I now have the breakdown and specific punches needed. Thanks.

Call apex, or call S&W with your serial number and find out when your CORE was made. Not sure if any COREs were made before the swap to the larger plunger. IMO it probably has the larger plunger.

However, you're going to have to take it all out anyway so why not measure it?

A few final notes regarding the M&P trigger pin installation. Much of the pleasure of gunsmithing is derived from fabricating simple tools or jigs to make
a task most hate to one that is welcomed. The basic problem with this task is controlling a spring-loaded part in a very small space which is why the
sub-assembly approach will be easier for most. I use these tools to perform the installation in seconds.
Finally, a simple modification to the Apex slave pin to make it a little better to use.

Ans. # 1. You use the drill bit to create a space in the yellow slave pin, then shaft of the drill bit is secured with Gorilla glue.
Ans. #2. IF you use the sub-assembly method then the first slave pin is too long, as both ends are now sticking out of the locking block. The second slave pin is the exact width of the locking block so you
can then drop the sub-assembly into the frame, then push slave pin #2 out with the Trigger Headed Pin. Done.