Depending on where the threads begin on the barrel and the sight, there may be an alignment issue when the sight is snugged into place. When there is a final alignment issue, a gunsmith can use various material(s) to backfill the original hole, to get the sight to align and secure. It is not advised to attempt this if you are not familiar with this technique as the material used can be difficult to remove.
TRUGLO recommends all sight installations to be performed by a professional gunsmith with sight specific installation tools.