I was reloading for several decades before I started using case gauges for the rounds I shoot in competition.
You will still need to “plunk” to make sure a particular combination fits in the barrel but as long as you don’t change components or settings, a case gauge can be a handy tool.
If it won’t plunk, you’ve obviously got a problem but the way barrels are made rounds can plunk in the barrel and drop free but then there is a “mystery malfunction” because you had already put every round into the barrel and they dropped free.
Generally because the barrel doesn’t check the rim at all and sometimes not much of the base (parts not contacted by normal size dies either) and a case gauge does.
Problem is when the case has to ride up the breechface, under the extractor and fails. Some times these rounds can be loaded again (clocked differently) and run fine. Also why not all case gauge “fail” rounds, will cause a malfunction, if clocked just right, the imperfection has no effect/contact with problem area.
Generally looks like this little ding in the rim, causing the case to sit proud in the gauge.
More often than not, removing a round like that and inserting it into the gauge rim first and giving it a twist, will iron out the imperfection and it will now drop into and out of the gauge. This is the #1 reason I prefer steel gauges.
A push through or roll sizer can fix the issue but are an extra step, the roll sizer can even clean up inside the extractor groove.
That said, I don’t case gauge all of my ammunition, but I case gauge every round I shoot in timed gun games. Right before I started using them, I had lost a match by two tents of a second due to the mystery malfunction (former plunker) and the guy that beat me picked up the round, pulled a case gauge out of his bag and showed me I could have prevented the failure.
Just have to decide if the extra work is worth it. Lots of people would have just chunked the problem round and went on having a good time to never think about it again. So they are not for everyone.
