I have a new X300, which I have outfitted with the QD option. The spring-mounted bar on the X300 will not engage the slot on the underside rail of either my Gen II G23 or my Gen III G20. I assumed that the small friction bumps on the front side of the trigger guard were preventing the X300 from being fully pushed against the trigger guard, so I filed these off. No luck. So then, I took another careful look and it looks like the engagement bar might actually be wider than the slot on the rail. Does any one know if this is correct? If not, any other hints on what the problem might be?