Take some pic's of the recoil spring area, as in the pic's below. Many guys don't remove enough material as in the first pic. Make sure the recoil spring recess looks like the second two pics.
Also make sure the spring for the slide latch is pushed fully down into it's recess. None of it should be above the polymer where the recoil spring and guide seat. You may need to remove just a bit of the tail of this spring so it fully seats below the recoil spring and guide.