Early in my gun collecting/reloading career, once I had scrounged enough brass in a particular caliber for which I owned no gun, I would absolutely begin hunting for a gun in that caliber, especially if said gun could fire more than one caliber either directly or via barrel swap.
I had a bucked of .40 S&W brass, and bought a set of .40 dies (from a going out of business sale at a local gun store) before I had a .40 S&W gun. Once I had that gun (SIG P229), I quickly sourced a .357 Sig barrel, and started down that road as well. Also, since I already had some .40 165 grain bullets in my inventory, I also bought a 10mm hand gun.
It's really a slippery slope once you get it real bad like I've got it.