First off,
Is the threaded section of the mag catch level with the surface of the mag button? If not, push the mag button all way in with a pencil, and spin the catch the needed turns.
As for the mag insert block, if needed, pull the catch all the way off (again the pencil) and check the insert block catch slot against the receiver slot. If needed, break out a file and remove some block metal to allow the mag catch to seat all the way down.
Last step, with the empty mag inserted, full stroke the bolt and see if the feed lips are contacting the bottom of the bolt. Also, you need to test this with the bottom of the mag push forward and back as well. The mag will have some movement in the adapter under recoil so you need to check the mags at both of it's deflections, and not just at free rest alone.