Recently I have avoided expanding my ammo supply logistics by not adding any new calibers in the past ten years.
There was a time (47 years ago) when my guns were limited to a
.32 S&W Long Iver Johnson revolver,
.22 LR Marlin Model 99G rifle,
.22 S,L,LR Winchester 69A rifle,
12ga Marlin 55 shotgun, and
.30-30 Winchester 1894 rifle.
Ammo supply was simple and basically based on specific needs: plinking, varmint, small game, deer hunting opportunities.
I inherited guns, received guns as gifts, took up sports shooting in muzzleloading, black powder cartridge, and vintage and modern military. I took the advice of acquaintances who were police officers and looked at defensive guns. Then the occasional historic and design curio appealed to me. Ammo supply got complicated.
I sometimes did consider simplifying my ammo supply logistics when I looked at new guns. Would a 9mm do any more for me than my .40S&W H&K USP except complicate my ammo supply? Pass.
Getting rid of some guns would be a hard choice. Many are inheritances or gifts with histories: the .303 sporter that my stepdad helped me get a good trade on then he gave me a .303 Lee Loader that Christmas. My son will inherit that. I can't see trading or selling it to a stranger even if it would eliminate an odd ball caliber.
I buy and shoot in my guns:
.410 shotgun
12ga shotgun
.22 Short, Long, Long Rifle
.22 Magnum
.25 ACP
7.62x25mm Tokarev
.38 Special
.357 Magnum
.40 S&W
.45 ACP
6.5mm Carcano
.30 Carbine
.30-30
.303 British
7.62x39mm
7.62x54R
I reload:
7.63 Mauser
.38 Special
.45 AutoRim (for a "cut" .455 Webley)
6.5 Carcano
.30-30 Carbine
.303 Brit
12ga
Reducing calibers might make my life less complicated, but I am not sure that it would make me happier.