Scope mounting: Use a side rail that clamps in with 3 hex screws. I had a quick detach one that only clamped down in the middle, and after 3 shots it would go flying off of the gun.
Make sure you get a good scope or red dot sight too, as the recoil can be quite hefty with some loads.
Trigger pull: From the factory, it's terrible. It's mushy and very long. If you convert it however, the trigger is out of this world (I use a Tapco g2).
Accuracy: Excellent with anything but the factory iron sights. Mind you, that front post covers about 6" at 100 yards, so a scope or red dot sight is crucial. If you take a look around on this site, there are several people reporting excellent results at 100 yards, and it is pretty common to see people making hits out to 600 yards on Youtube.
Other quirks: I find the best mags are made by CSSPECS. They are literally indestructible. Also, under no circumstances should you put a muzzle break on this gun. The concussion from a 16" barrel is unbelievable to anyone that isn't shooting the gun, and there's no need to make it louder. Screaming "fire in the hole" before shooting isn't a bad idea either...