I currently own 2, a G19 that I purchased new in the mid 80s and have fired several thousend rounds through with zero problems, and a G36 with a lot less shots fired and no problems. Also had a G26 which I sold to my son-inlaw. They make a very reliable weapon, with over 25 models.
Here are some facts from other sites. The Glock proved overwhelmingly successful and as of 1992 sold approx. 350,000 pistols in over 45 countries, of that 250,000 to the USA.
It is supposed that a good modern pistol's barrel and mechanisms must serve not less than 40 000 shots. The "Glock" Gmbh specialits claim that the "Glock-17" and other models serve approximately 360 000 shots that is a really impressive number. John