While you have the muzzles hanging out, are they threaded or pinned? Any idea on thread pitch?
It is definitely threaded - the Flash-Hider has flats for a wrench, however I strongly suspect that heat will be required to overcome some form of LocTite/Rockset thread locker.
Here's mine with a new Riton 3-18x 50mm Scope in an American Defense QD Cantilever Mount all ready for accuracy testing next week (weather permitting). I suspect that this rifle will soon find itself wearing the new Arken EP8 FFP 1-8x 28mm LPVO that I have inbound with arrival next week. I have a set of MDT 34mm Rings that will do until I can find a suitable Cantilever mount. I will be going with a Holosun HS 507C in a 45-degree Right-side offset mount as my back-up in the absence of Iron Sights. I find it very bizarre that they (FAMAE) decided to dispense with the existing Iron Sights that were in place. Th rifle looks odd as a result of the omitted Front Sight...

One thing that I immediately noticed about this iteration/production run of the SG 542 is that they appear to have a much finer finish than before. I don't know if FAMAE is now using some type of powder-coat finish instead of the usual thick epoxy paint, but the paint over the parkerizing is definitely thinner and "neater" than before. The markings are actually legible this time!
