Yes, it certainly can be caused by a defective primer or one that has been compromised for example someone using WD-40 on their weapons since it is a penetrating oil. Not a good gun lubricant.
But in other cases it can be caused by a short powder drop charge or in some instances no powder at all and the primer ignition drives the bullet into the barrel of the pistol.
The main thing is pay attention to your pistols and if something seems, feels or sounds different "Stop Shooting" until you check it out! Squibs can happen!
The Constitution is not an instrument for the Government to restrain the people. It is an instrument for the people to restrain the Government!
America will never be destroyed from the outside. If we falter and lose our freedoms, it will be because we destroyed ourselves.