I have heard it said many years ago and I am guilty of repeating it as well, but "A man can't do any better work than the tools he has to work with."
To wit, I get a lot of aftermarket barrels sent in for throating, Kart, Lone Wolf, KKM, and the owners don't realize that not only are these barrels made under tolerance for some gunsmith fitting, but their chambers are also short reamed and there is virtually zero throat, this is so the smith can set headspace and then cut the throat in the barrel once the hood and the lugs have been fitted. Since some of them will work with no further smithing, the owners often think there is nothing wrong, when in fact they skipped a pretty important step in proper fitting of the barrel and this is setting headspace and throat reaming to put the icing on the cake.
I needed a better tool to measure this than the stilt leg of a cheapo vernier caliper so I set about making this from a Mitutoyo Digimatic Micrometer Head I got from ebay for about $50 or so. All it took was a little machine time to make the collar and fit it with a locking screw, then make a plunger that will zero with the micrometer and sit in the end of the chamber for measuring. About 2 hours work total and success is sweet! I have wanted and needed one of these puppies for years and years and finally I have one!