I think everybody uses different formulations so if you buy tubes by Reynolds, Columbus, True Temper, Tange, KVA, etc., it's all a little different. I think the term 4130 has devolved somewhat into a description of higher end pipes. I pay attention to diameter and wall thickness rather than what's in the steel.
Seamed tubes used to be low end but True Temper OX platinum is seamed and it's very good stuff. Don't run away from a modern tubeset just because it's seamed.