I figured the trigger might have issues with the harder primers, but gave it a shot. My timney didn't work either. I don't plan on running junk, but I do want to know I can, so I think I'm going to try a hiperfire and move the mecharmor to a 5.56 gun.
For the front sight....The matrix has a AR10 height receiver rail, which is obviously a little higher over bore than an AR15. PRI makes a separate AR10 front sight to make up the difference when using a normal rear sight. Its only a tiny difference and the standard sight probably has enough adjustment to work, but I didn't realize there might be clearance issues so I bought the "correct" part for the build (that turned out to not be the best option) all worked out well.
Jury is still out on the 1-6. Glass is beautiful and eye relief is great but I only shot at 50yds. Its heavier than the aimpoint, and 6x isn't really that much magnification so I'll decide if it's a workable compromise when I start pushing out Or if I need to try something a little bigger. I still have the weaver tac 3-15 laying around but that thing is a pig. Rifle is too heavy for my small scale and too light for the big scale to get an accurate weight on it so I'll have to do it in parts when I get around to it, but it's sure not light.