IIRC the Arcus uses a trigger design similar to an early S&W semiauto.
I'm a bit intrigued by this due to my fondness for S&W TDA pistols.
Does the Arcus incorporate a trigger-actuated firing pin block? 1st-gen S&W pistols do not; these pistols have a single plunger under the slide for the mag disconnect, a corresponding lever in the LH frame that doubles as the ejector, and a second lever in the RH frame to disengage the sear when the decocker/safety is operated. The 2nd- and 3rd-gen pistols added a second slide plunger and another lever on the RH side for the firing-pin block.
Also, FWIW a frequent errors when reassembling a S&W TDA is failure to reinstall the disconnector correctly; it's a vertically-oriented part located in a hole in the rear of the frame. The tab on the disconnector rides on top of the trigger drawbar, and it's supposed to point towards the rear. The problem is that the disconnector is hard to see, so if you disassemble the pistol without instructions, you may not realize it's even there until you remove the drawbar, which will cause the disconnector to fall out if you're holding the frame open-side up. (clink... "What's this thingy that just fell out?!?")