I also have a PT99, this is nice to know.Replace the locking block - its a cheap part. If the newer Beretta locking blocks will fit it, opt for one of those. They are the weak point in the pistol. If the Locking block breaks, it can lock the slide, barrel and frame together to where the "fix" is cutting the barrel to get the gun apart. I used to own a Taurus PT-99, and I am speaking from experience.