I had the same problem. My XCR was hitting low even with the front sight all the was down(Samson front sight). I ended up filing it down till I was very close to right on at 25 yards and then I re blued the sight post. Be carefull not to file to much off or you will be high.
You can also but a set of front sight posts ans swap them out as needed.
You can also but a set of front sight posts ans swap them out as needed.
