531 was the best available in the 30s-70/80s - but then Columbus SL was introduced and proved to be equal/slightly better - prompting reynolds to make 853, 631 etc (air hardened) I can't remember the differences b/w 531 and 531c (competition) - but guess it is just a thinner version?
531 was the best available in the 30s-70/80s - but then Columbus SL was introduced and proved to be equal/slightly better - prompting reynolds to make 853, 631 etc (air hardened) I can't remember the differences b/w 531 and 531c (competition) - but guess it is just a thinner version?