I was going to suggest looking at the SAAMI drawings and that you could make a gauge if you have a lathe, but to save the price of the Brownells gauge, it isn't worth your time to mess with it, IMHO. Indeed, if you
look at the manufacturer's site you save a dollar on the price. Of more interest to me, the manufacturer's site also has
a set of two gauges, one for small and one for large primer pockets for $20. They also have a
set of 3 different gauges for $30 that includes both the large and a small primer pocket gauges and a taper gauge they call a neck tension gauge for both 223 and 308. The taper on that gauge has diameter calibration marks to let you sort cases by the ID of the resized case mouths. So it's really a case mouth interference fit gauge, but you may find that useful. If you get necks that stop sizing down enough, the brass is getting springy and needs annealing. You may even want to sort your match load brass for matching interference fit.
I've always used pin gauges or small hole gauges to make the primer pocket check, but these gauges are too convenient to ignore, so I am going to order a set of my own.
One last thing is to point out is that if your primer pockets are getting loose in just a few reloadings (say, five or less), that is generally considered a pressure sign. It may or may not be excessive pressure for the gun but it is for the brass. There is some significant variation in head hardness among different brass makers, so it may do fine with other brass but not the lot you have.