Take everything here with a grain of salt.
A buddy of mine is a gun store clerk and has a bag of broken locking blocks to warn people, but he's a Berettaphobe.
I only have one first-hand account of a locking block breaking. I was at the range and a lovely lady whom I know to frequent the range was shooting her 92SB and hers broke. She puts in several hundred rounds of Winchester Whitebox a week and the Walmart clerks know her by name and she buys the stuff by the thousands.
I read somewhere (take with a pinch of salt) that they changed and improved the locking block design but I can't confirm this. Heck I can't even remember where I read this or if I dreamt it. I'm running a search at Berettaforum right now for 'locking block' but it's getting close to 80 results so I'll do some digging tomorrow.
Again, take everything here with a pinch of salt, I don't know the circumstances of my buddy's broken locking block collection or the condition or history of my acquaintance's 92SB.