Sig Sauer MPX-9 Gen 2

[FireMoth]

So far as triggers, the Gen2 is less prone to hammer and disconnector breakage then the Gen1, due to a smaller gas port and lower bolt velocity. However, not all AR type triggers will survive. We have had great luck with the HyperFire 24c/3g, both because its a ridiculously fast trigger, and because the booster springs delay the bolt a little on opening, and ensure positive ignition.
BCM and Magpul AR grips seem to fit well, as do selectors from Radian and Battle Arms, and charging handles are available from Radian now.