Least practical handgun?

[Mr. 16 gauge]

O.K., so what is the least practical handgun in your collection? By least practical, I mean a sidearm that you don't/can't shoot as often as you might like, for a variety of reasons: ammo is scarce, expensive, or nonexistant; the gun is too valuable to shoot; the gun has a 20" barrel or some other feature that makes it unwieldly, ect.

For me, I'd have to say that my least practical handgun is my 1920 commercial DWM Luger. It does get taken out and shot from time to time, but with ammo difficult to find (as is reloading components), and running greater than $1/round when I do find it, it spends most of it's time in the safe. Not to mention spare parts aren't all that common, either, and if something breaks then it just might get relagated to the position of wall hanger!

So what is the least practical sidearm that you own?