I have had squibs,mostly when I was shooting trap and loading lots of shells.Once in a while the charge bar on my progressive loader wouldn't move right.I remember it happening during a shoot and the wad lodged in the barrel.I had no clue what to do,but an old timer yelled at me"blow in the barrel!".I did,and the wad popped out and I finished that round with a 24,thanks to the squib.Most of the time,there is just plain human error.Whether it comes from a lack of experience,education,or just not being cautious,it does happen.I don't do any progressive loading any more,but am a stickler of detail when I am loading ammo.I learned the basics from a very patient uncle who took the time to get me started in metallic cartridge loading,and some of the tricks he taught me about loading reliable ammunition have stuck with me through the almost 40 years I have been loading.I think it is far easier to get in trouble with a progressive machine due to the fact that they are busy,complicated tools that must maintained and adjusted for them to work right.Too many newbies are trying to run before they learn to walk by buying a progressive and trying to learn the basics with a machine that they don't really understand.A squib load is one thing,a double charge can be a whole different kind of disaster.Internet or not,there is something to be gained from having a wise set of eyes looking over your shoulder when you're starting out.I think that experienced reloaders should always be willing to help somebody who is just starting out.I think the best way to learn something is to teach it.I go through a tray of brass in a certain pattern during each step of the loading process,and it only takes a few seconds to look down in the case mouths as they sit in the tray and make sure the powder is at the same level in each one before the seating process begins.