Another thing I noticed is the ejector drags a bit on the frame. Without an ejector installed, the receiver slides effortlessly on the frame. With an ejector installed, some effort is required to slide the receiver along the frame.
Looking at the design, this seems inevitable. As shown on the attached photo, the hole for the round tab is truncated (just barely) by the slot in the receiver that engages with the frame. Also, the bottom of the hole is (barely) visible beneath the installed ejector.
When the receiver is fully inserted, with the toggle engaged, I cannot discern the drag between the ejector and frame.
Is the ejector rubbing on the frame normal?