Hello. I just found out that I won the APEX Tactical Competition Action Enhancement Kit. I was asked which caliber I have, and I was wondering what the differences were... I currently shoot a M&P .40 full size in IDPA, but it is all stock and has had no modifications to it. I plan to purchase the M&P 9mm Pro series in the immediate future for use in IDPA, and just keep the M&P40 for carry/ self-defense purposes. The parts that come in the kit are listed:


Apex Tactical Specialties is proud to introduce it's new *Competition Action Enhancement Kit.
Designed for the action shooting sports competitor, our drop in kit will yield a consistent sub 3 lb trigger pull. Whether the game is IDPA,USPSA or Steel Challenge our Comp-AEK will withstand the rigors of high speed competition.

The kit contains:

•Apex Hard Sear
•Apex Ultimate Striker Block kit
•Apex Competition striker spring
•Apex Competition sear spring
•Apex Competition trigger return spring
•Apex Aluminum Slave pin for installing the Trigger Return Spring

Our competition striker spring and trigger return spring are shot peened to extend service life.

I have never modified any pistols before nor have I ever had any trigger jobs done. My question is this: Which parts would be different and which parts would be interchangeable between the M&P.40 with a 4.25" barrel and the M&P 9mm Pro series with a 5" barrel?