I think it's going to depend on the ammo and gun you have.
Unless your handgun has a free-floating firing pin (like the AR15 involved in the story about repeated chambering and a primer failure), the primer should not be damaged by repeated chambering. Normally, a primer is flush or below flush when seated in the primer pocket. The primer isn't abused in the cycling of the action. Bullet setback does not effect headspacing. Headspacing has to do with how the case fits in the chamber and how the shoulder or neck of the case touches the chamber. Bullet setback could negatively impact ammunition feeding due to the shortened overall length and case mouth protrusion from where there should be bullet material.chambered repeatedly it can cause the primer to possibly go bad (?) or for the bullet to be pushed back into the brass, causing headspace.
From what I know, the problem is not in keeping a round chambered for a long time as most modern and quality ammo will not have any problems. The problem has been studied and found to be when you keep chambering the same round over and over again. For instance when you come home each day and extract the round in the chamber and then put the same round back into the chamber the next day. That will cause problems as the round is being pounded into position each day and supposedly that affect the round and makes it less reliable over time. I guess it pushes the bullet further into the case a little at a time and if you look at bullets that have been chambered a lot you will usually see nicks in the case and sometimes it looks a little deformed.
I shoot my carry ammo at least once every 3 months so I always have fresh ammo. I know guys who have the same ammo in their gun for years due to the cost of replacing it. One had the same ammo in his gun for 25 years and it went bang when I finally got him to shoot it.
Regardless of the pistol maker the .40 s&w is a problem when there is bullet setback. In some loads it takes only .01" setback to increase pressures in a .40 well past SAAMI maximums.Unless your handgun has a free-floating firing pin (like the AR15 involved in the story about repeated chambering and a primer failure), the primer should not be damaged by repeated chambering. Normally, a primer is flush or below flush when seated in the primer pocket. The primer isn't abused in the cycling of the action. Bullet setback does not effect headspacing. Headspacing has to do with how the case fits in the chamber and how the shoulder or neck of the case touches the chamber. Bullet setback could negatively impact ammunition feeding due to the shortened overall length and case mouth protrusion from where there should be bullet material.
Bullet setback can cause dangerously increased chamber pressures. One type of propellent in one kind of ammo might not cause disastrous effects from setback while another kind may cause a kaBoom. There are reports on the internet of obvious (purposely induced) setback causing no problems and also reports of setback blowing up firearms. I recommend minimizing the number of times you unload and reload your firearm. The only times my handguns are unloaded (unchambered) are during trips to the range, showing them to a friend, dry fire practice and maintenance.
2nd generation .40 Glocks are notoriously susceptible to kaBooms because the barrels have less than desirable case head support, leading to a case rupture near the case head when the user is unlucky enough to shoot a round that is abnormally overpressure or has a weakened case. The 3rd and 4th generation chambers are much improved. Be careful.