I recently experienced a broken locking block and trigger pin in a G27. The retaining pin was beat but unbroken. Estimate, about 7-10K rounds on original locking block. But I had replaced both pins about 500 rounds prior. I initially thought that the trigger pin must have gone first and then the locking block. However, I thought some more and two points occurred to me. First, I had replaced both the trigger pin and retaining pin about 500 rounds prior to the break. Second, just looking at set up and envisioning operation made me wonder, if locking block is what really takes the pounding and function of pins was mere to hold locking block in place. Naturally once locking block breaks the pins will start taking some pounding, as they are now holding locking block together. Basically, one leg of locking block sheared off. Similar to most pictures you see posted. Sorry I don't know how to post pictures. So in these cases where you see a locking block and one or both of the pins broken, which do you think went first? If the locking block is going first, as I now suspect, it will not do much good to just replace the pins as a preventive measure. The locking block and probably pins will be what needs to be replaced as a preventive measure.