Speaking of, I don't know if guns count as tools, but there are still things about them that piss me off. British .303 is actually 0.310-0.312" in diameter, or about 7.9mm. .38 Special is actually 0.357", .327 Fed Mag is actually 0.320".
.308, .30-06, and .300 Win-Mag are all 0.30" (7.62mm) diameter. 7.62x54mmR does not conform to any existing nomenclature scheme except itself.
.380 ACP, .380 Browning, 9mm Kurz, and 9mm Short are all different names for the same thing and all are in common use, and all are 9.0mm or 0.357" in diameter. 9mm Makarov is actually 9.22mm, while 9mm Parabellum is 9.0mm.
.22LR and .22 Magnum use the same diameter bullets, and while .38 Special will fit into a .357 Magnum chamber and .44 Special will fit into a .44 Magnum chamber, .22LR will not fit into a .22 Magnum chamber; or rather it will but will cause the gun to malfunction.
There are reasonable historical reasons for all of these things. That doesn't make them any less infuriating.