Here's some ballistics that I found very easily!

There is, in fact, a caliber called the Ferguson .257 Hot Tamale. Here are some amazing ballistic stats on it I found in one online post.

A muzzle velocity of 4,060 fps with a 100-grain, all-copper J-36 bullet (manufactured by Lost River Ballistic Technologies Inc.) and a ballistic coefficient of .532:
+ 1.89 inches at 100 yards
+ 3.15 inches at 200 yards
+ 1.78 inches at 300 yards
Dead-on at 350 yards
– 2.58 inches at 400 yards
– 10.27 inches at 500 yards.

Velocity at 500 yards is still in excess of 3,000 fps.

Energy in foot-pounds generated at the muzzle is 3,660, and at 500 yards, it still maintains 2,057 foot-pounds of energy which is more than adequate for deer-sized game.

The post was from Buckmaster's Gunhunter Magazine in an article by Russell Thornberry. At the time it was written, the .257 Hot Tamale was billed as the fastest-shooting .25 caliber wildcat on the planet. The article sourced the following as contact information if you'd like to inquire about having the gun built and ammunition made.

Ferguson Custom Rifles, 5320 FM 1299, Wharton, TX 77488
(979) 533-0140, (979) 532-4799;
Fax: (979) 532-4108

Lost River Ballistic Technologies, Inc.
P.O. Box 80, Arco, ID 83213
(208) 527-8611[/align]