Would I be correct in assuming you primarily shoot at a private range and also mostly only pick up brass that went through one of your chambers ? Much chance you could get some brass mixed into yours from a gun with a chamber with questionable support ?
Curious as to how much you would guess that percentage would change for the reloader who commonly frequents a public range and picks up brass from many other shooters... I ask this because I often times shoot at a public range and many times come home with several hundred casings where the shooter didn't want them. It only took a couple times getting bulged brass mixed into my can that I easily justified spending the $15.00 for the gauge. My wife and son both know if offered brass, it only goes into the can if it drops about 80% of the way into the gauge...
I fully understand I could always tote one of my tighter barrels to the range.... I could always tote my calipers to the range also.. But given a choice of a 15.00 tool or a set of $150.00 B & S calipers, I leave the calipers at home.
I think there might be a misconception on those who justify having the gauge... I do not randomly check every so many rounds... I use the gauge at the range like mentioned... I have on a few occasions loaned it out to help troubleshoot not going into battery issues... I very seldom use it at the bench... I only use it at the bench only when I know something just didn't feel right, which would be in the sizing or the crimping step...
Being I've defended my justification for using the gauge and to be fair, I will disclose (1) circumstance I learned first hand where I would have to admit the gauge wouldn't be worth $.05 in scrap metal.... A few years ago I was shooting a favorite 9mm load using Missouri's 125 gr small ball... The ogive was quite a bit more blunt than your typical 124gr NATO RN jacketed... I had a load for the Glocks, a FN, and a few more platforms that I really liked so I spent the winter loading quite a few for the following spring/summer... I added a XD the the mix, and even though the gauge said everything was fine, the ogive would embed into the rifling about .060 before the gun would go into battery...
Do you not FL size your brass? I ask because I often bring home range brass or buy brass at gunshows. After FL sizing I've never had an issue with sized brass fitting into any chamber, Even with Military brass shot in machine guns.