u_gonna_squeal_b4_we_cookya :
I'm guessing that most of these 1911 mis-fires due to worn sears are on 70+ year old guns or on guns with poor blued or parkerized finishes. If not, then it is more likely to occur in a combat environment than a typical home/suburb environment. A finish like that out in the desert or sea is almost like not having any finish at all. Salt and sand will rip it all off like sandpaper. According to the last link that 4Ryan6 posted, good hammers and sears should be made from tool grade steel which is extremely durable. If you have such a hammer and sear and keep the overall gun maintained properly, carrying a 1911 cocked and loaded should be as safe as carrying a loaded Glock or Beretta 92. There is also the possibility that many of the sear failures were caused by the user carrying the gun with a half-cocked hammer. This is supposed to be very bad for the sear and it is recommended to either keep it fully cocked or not at all. I did find many of those sites very interesting and have learned a great deal more about the gun I have been carrying for the past 4 years now. Just like with any subject, I learn something new just about every day. Only this subject could potentially save one of my family member's or my own life which is why I want to know as much as possible.
On ship we had a 270 man crew we normally allowed them to fire at least 2 mags through the weapons, if they could be trusted with one, that gave us the opportunity to see how comfortable they were with the weapons.
Those that were high rated such as watch standers could practice up to 5 mags but our ammunition was not unlimited we had a certain amount allowed to use up for training purposes.
However the 1911s we had set aside for training purposes had an enormous amount of rounds fired through them, they had to be completely broke down after each session and inspected for wear.
Our replacement parts were seriously limited, we had damaged guns from being dropped and abuse, mostly from those that ended up not being approved to be handed a weapon at all, even in a crisis situation.
Some people just cannot handle a weapon and no amount of training will make it possible, and we had to discover who we could depend on if the need arised, so we had to weed out those that couldn't, and nourish those that could.
Cycling through a 270 man crew put a lot of wear on our weapons which eventually led to the 45acp sear failure, plus the salt air environment was extremely harsh as well, we had to reblue many weapons.
So to sum up, if gun lover A, decides today to go buy a brand new 1911 from his local gun store will the sear fail, no of course not!
The amount of wear it would require to reach a point it fails to stop the hammer, is almost unmeasurable!
However is it possible for a sear to become so worn it fails to stop the hammer resulting in a run away, Yes it is!
There are other negative sides discovered over time regarding the 1911 that I supplied links to way above, such as jamming with various types of ammunition, but there are fixes to those issues.
The original gun design fired round point full metal jacket rounds, some of the newer hollow points rounds can jam, basically because of the shape of the end and the tip being lighter.
The Hornady Critical Defense 45acp hollow point round should by it's design never jam, that's what I use.
Additionally improper loading of the magazine can cause a jam even with full metal jacket ball rounds, if the bullets are staggered front to rear loaded in the magazine it can cause a feed problem as the bullets are pushed up to the slide as the magazine feeds the weapon.
After the magazine is loaded lightly tap the back side or primer side of the magazine on a flat surface to get all the bullets in alignment with each other that ensures the smooth feed to the weapon.
Most every jam we experienced during ship training was simply caused by the bullets not properly aligned in the magazine.