I'd go with rl22 or rl23....
The standard load for a 300win with a 180 and alliant powder has been 75 rl22 with a 215 lighting the fire for years... Work up to that with your ttsx as the bore drag may well be different than lead core pills... 24" bbl.'s are usually able to get just above 3100 fps safely with a 180 and rl22; 3150 fps with a 26" tube...