Yes, it will.
The manufacturer states that these triggers are specifically for AR platform rifles and will fit most .308 and .223 AR-style platforms.
This trigger uses mil-spec (small) pins which are typically a .154" diameter.
These triggers are specifically for AR platform rifles. This will not work any other guns except for ARs.
Yes, this trigger will fit a M4E1 Lower from Aero Precision
RISE Triggers are compatible with 7.62x39 AR's. If you have an issue, feel free to email help@risearmament.com
Yes, the RISE Armament RA-434 High Performance Trigger will fit and function in an AR15 platform rifle chambered in 300 Blackout.
The RISE Armament RA-434 High Performance Trigger will work in an Aero Precision M5 Lower.
The RISE Armament RA-434 High Performance Trigger might fit the MPX Gen 2 but I recommend using the MPX specific trigger at the link below.
https://www.opticsplanet.com/timney-triggers-sig-mpx-single-stage-drop-in-trigger.html
The RISE Armament RA-434 High Performance Trigger does not come with trigger pins. You will use the trigger pins in your AR install the trigger.