I'm assuming that you're using the PMI EVO Special Edition.
You might need to file the threads down a bit, but thats highly dangerous, you could ruin your feedneck that way, since the threading sticks out too much for the EVO. You might have better luck using a ICD threaded feedneck.
You could also tap the body to actually accept the feedneck if you have the right size.
Other than that, there really isn't much that can be done