In addition to magazines, I routinely buy ammo for guns that I do not have yet.;-). Not a problem.
Ha!!!

Now, that's something I never thought of doing before.

Perhaps with the challenges we face now and the likelihood of far greater challenges after November, it's something I should seriously consider.
I guess the question is: What calibers might I someday need for which I don't have any matching guns right now.
I recently bought some .357 Sig ammo after acquiring a .357 Sig barrel for my M&P40 FS... so that's good for now. I also stocked up recently on "non-Plus P" .38 Special so I could use that in my vintage Model 10-5.
I don't own any .32 ACP ammo... nor do I own a .32 ACP pistol. I suppose it's a long shot possibility that I could own a Seecamp .32 someday (the .380 version is not for sale in MA).

But with very few "good years" left, that's kind of doubtful.
10mm is one obvious choice, but the ammo is crazy expensive here in MA. Walmart doesn't even carry it. From what little research I've done, it appears like you've got to buy it on-line to get it at least semi-economically... but we can't import here in MA.
I own just one shotgun right now and it is .410 gauge. I guess one could make a pretty good argument that I should own some 12 gauge shotgun shells... just in case the stuff hits the fan really hard someday!
A friend recently got me fairly interested in the Ruger SP101 .327 Magnum revolver. If it ever goes on sale cheap enough, I could see myself going for one of them... so there's a fairly decent candidate!
Only other one I can think of is FN's 5.7×28mm cartridge for their PS90 bullpup. It makes no sense for me here in MA with our silly magazine size restriction, but the gun itself has always intrigued me and the price has come down a lot from a few years ago. I'm certainly not going to run out and buy one tomorrow... but I wouldn't rule it out entirely either.
