I believe, and I have believed for a while, that we live in a golden age of riflery. Better rifles than every before, more accuracy, better powders and better bullets. Much better bullets.
Back in the day, 1906, to be precise, we got the .30-06, a whiz-bang cartridge that improved on the older .30-03. The new .30-06 pushed a 150 grain bullet to the unheard of velocity of 2700 fps. Perfectly suitable for every shooting task, and quickly adopted by various military formations. Indeed, today that same cartridge, pushing that same 150 grain bullet to that same 2700 fps is perfectly useful, but nowadays it's considered anemic. It's little brother, the .308 Winchester, pushes that same 150 grain bullet to the same 2700 fps, and in practice, handloaders often do better. We've got better powders. Today, I can flirt with 3000 fps in the .30-06 and a shade over 2800 fps in the smaller .308, simply because we have better powders.
Back in 1915, a fellow named Charles Newton developed a cartridge based on the .300 Savage. The .300 Savage case is roughly equivalent to the .308 Winchester in capacity (and I'm speaking in broad generalities here). But, Charlie Newton was a fan of the quarter-inch bore, so he necked that big case down to .257 and stuck an 87 grain bullet in it. A new cartridge was born, the .250-3000, so named because it pushed that 87 grain bullet to 3000 fps, a whiz-bang velocity for that era (and nothing to sneeze about today). Today, the .250-3000 cartridge is almost deceased. I don't know of any major manufacturers who build a rifle chambered for that cartridge. It's mostly a custom proposition, although the caliber still has its advocates.
In the 1980s, a fellow named Wes Ugalde started playing the Thompson/Center Contender, a long barreled single-shot pistol. He re-necked the .223 Remington cartridge to larger sizes, making a whole family of cartridges for that pistol. His most famous design necked that cartridge to 7mm, but he built a whole family of cartridges, to include the .25 TCU, the 6.5 TCU, and the .30 TCU, all based on the diminutive .223 cartridge.
Powders get better, allowing us to push bullets faster, to put more energy into smaller spaces, and last year, the new Sharps Rifle Company came out with their .25-45 Sharps cartridge. Designed to run through the modern AR-15 rifle. It pushes an .25 caliber, 87 grain bullet to 3000 fps, just like Charlie Newton's wildcat did in 1915, but it does it in a much smaller package. What's the difference? How can the guys at Sharps get the same performance out of a much smaller package? Better powder.
I admit that I like .25 caliber cartridges and I profess a fondness for small, light rifles. I was thinking last year of building a rifle in .250 Savage, but now that I've found this new wildcat, I'm doing some pondering. The smart money would be to wait another year, to see if it catches on, or just becomes a niche cartridge. But, I admit that scrolling through the Sharps Rifle website has me pondering.