This is actually a requirement for any firearm displayed at the SHOT show, at least for the last 15 yrs. officials visit each stand, check firing pins are removed/non functional and attach an inspection tag to the trigger guard. Not saying its practical for individual older guns, relatively easy for original manufacturer of a new gun for display purposes only. That's the way it is.

Hugh Lomas,
H.G.Lomas Gunmakers Inc.
920 876 3745