A.R.T. 3-Position MPA Defender Active Reset Trigger System

Advanced Reset Technology builds the most complete MAC-pattern reset system on the market. It is not a single trigger part but a hardened steel reset lever paired with a 3-position selector: position one is the safety, position two is traditional semi-automatic fire with the reset feature disengaged, and position three engages active reset. That second position is what separates it from every other MAC FRT, which are all one-part devices you either have installed or do not.

Fitment is narrow and the vendor is specific about it. Compatible models are the MPA30T, MPA30SST, MPA930DMG, MPA930SST, MPA935SST, and MPA9300SS. Velocity VMAC variants, Cobray-pattern guns, and .45 ACP MPA Defenders are listed as not compatible, and .22 LR is untested. One of the three MPA bolt patterns drops in; the other two require fitting. If you own a Cobray M11/9, this is not your trigger, and the 3DP stainless unit is.

At $264.99 with a 4 to 8 week small-batch lead time, it is the most expensive MAC option by a wide margin. It is also the only one with a lifetime warranty on the reset levers and selector cams and the only one built around a selector rather than a single sacrificial part.