Favorite uncommon calibers

A Ruger No. 3 in .22 Hornet crossed my path many years ago. That's just too much work reloading for it for the return. It is fun to shoot, but jeminy crickets!

Dean2, I have some .30-30 brass that was necked up to make .375 Win. Although I believe that it is at the 2.02" length. I really haven't explored the cartridge much, but I do recall reading that Buffalo Ammo page a long time ago and was actively looking for a shooter .38-55 Commemorative when I stumbled onto the M94 Big Bore.
My guns are of Europe calibers. I am set up to reload them
and my most uncommon is 10.3mmX60R rifle caliber (.416) The seller, Jerry was friends with J.W. Hornady. Jerry had bought a Cape gun because Hornady had the die setup in his catalog, but when he tried to buy the dies, he was told that Hornady (company) never had made them.

Jerry, called J,W. Hornady (whom he knew) and complained that he had bought this Cape Gun because the Hornady catalog said they made the dies. J.W. laughed and had a set made. I have the only dies made for this caliber.
With the rise of all the new latest and greatest cartridges coming out year after year, I feel this list will include some that are currently being marketed hahaha. We have seen the fall of 224Valkyrie, though you can still buy it on the shelf. Will the 360Buckhammer, 6ARC, 6.8Western, 350lgd, 300spectre, Any Weatherby RPM, etc.... be on this list in the next 20-30 years?
The un- popular ones that I favorite
41 mag
414 supermag - looking for a longer encore barrel
444 marlin
257 Robert
404 jeffery- Ruger #1
16 gauge- Winchester model 12
I was thinking of building a 338-06 or a 35 whelen. But can't decide between the 2. How do like your 338-06 and do you think it's worth it over the reg 06 using 200 grain pills?
I used to shoot a lot of IHMSA silhouette. My favorite revolver cartridge was the .375 Super Mag. Then Dan Wesson came out with the .445 Super Mag. Traded the .375 for a .445 .

In an 80 round match the the recoil of the .445 would get to me. The last couple of banks of rams was a real struggle. 40 round match wasn't all that bad.
I acquired a EA Brown pistol a while back, it's chambered for a .357 Maximum case necked down to 7mm. Muzzle whip is horrendous, if I didn't wear a glove the pistol wanted to jump out my hand. Interesting piece but quite a handful.