15-05-2018, 09:13 PM
I have a lot of old R BSF/BSW bolts and are distinctly more strong than mild steel. I understood it to be the standard hardware HT. Does anyone know just what standard was/is the basis? A 1969 publication seems to imply S only for UNF/UNC and slightly more strong than R. Obsolete standards are a problem as anything can be claimed, as with API SF, SG, SJ etc engine oils.