Quote Originally Posted by Jamie
You will need to replace the bolt head for anything other than a .223 Rem.
...or related cartridge. There are lots of cartridges that are related to the .223 that use the same sized bolt head. These range from the .17's (Rem, Mach IV, Fireball) to the .20's (Tactical, practical) the .22's (.222, .222 Mag, .221 Fireball), 6mm's (6x45, 6x47, 6mmTCU, 6 Whisper) 6.5mm's (6.5PCC (wildcat), 6.5TCU, 6.5 Whisper), 7mm's (7 TCU, 7 Ingram, 7 Whisper) .30's (Whisper/221/Fireball, AAC Blackout) and even .338 (.338-223 Straight).

Several of those are fairly well established wildcats and load data and dies are pretty common.