I would not recommend my 257 Allen Mag for someones first shot at a wildcat round. Its not hard to load for but its as extreme as it gets in a 257 caliber round.
These are three of the 257 Allen Magnums flanked by two standard 25-06 rounds.
Performance wise, near 4100 fps with a 100 gr bullet, +3300 fps with a 156 gr Ultra Low Drag bullet.
The 280 AI is a far more practical wildcat to get started with. Nothing more then the 280 REM with a sharper shoulder angle and shoulder diameter increased. You can simply shoot factory 280 Rem ammo in the 280 AI rifle to form brass and your ready to roll.
Forming the 257 AM is a bit more complicated as its based off the 338 RUM case.