I took the XR920 apart to try to understand the difference in the trigger quality between it and my MR920. The trigger bar and connector both had burrs that you could snag a fingernail on where they interface on the trigger bar radius. The vertical leg of the bar that engages the FPBS had a burr as well. In the upper, the striker spring cups had burrs or molding slag on the external portion where it rides against the sleeve. I polished the burrs off of the bar and connector, installed a 5# striker spring, and replaced the spring cups. It is easily 60-70% better.