The beretta M9 is a POS for a military pistol. They do crack/sheer off loking blocks and slides have cracked. 9mm NATO is a stiffer load than the regular 9mm loads we tend to buy and it beats them to death. Go to most any range that rents a variety of guns and the person who repairs them will say round for round the most repaired gun is the beretta. I know of one armorer who got sick of replacing locing blocks and put in some from taurus. He got 15k rounds out of them instead of the usual 2-3k. Now from personal experience the problems are more prevelant in Beretta USA guns instead fo Beretta Italy guns. The italian pistols just seem to be made better in terms of fit and finish as well as duability. The slide cracking isue did happen with some Italian made guns(the first run delivered o the US before Beretta USA got up and running) and this was traced back to a subcontract out to a french company where the slides were not treated properly and became more crack prone.
They have gotten a bit better in maryland in making guns but not much. Locking blocks still break and everyone in a while I still hear of frames or slides cracking. The new main issue is the fact they are jam prone in a desert enviornment, being very picky when it comes to sand. This tends to be a real issue with teh mags as well and you can now buy slightly better "sand resistant" mags for them.
To sum up Beretta has had the contract for 20 years and the pistol has been involved in a handfull of conflicts and they are wearing out really realy fast. The colt 1911/1911A1 was last delivered to the government in the 1940's and saw ww2, korea, vietnam, and a bunch of other police actions and we still have them around in our arsenals. Thats speaks volumes about the quality of Beretta m9 pistols. Eventhough most of those colts have soft metal by todays standards and are loose as hell, they still keep running. Shoot a loose beretta and it will fly apart or not work.