I got this in a trade with a member here (never fired) till today and tried a lot of boolit/powder combos but still unsure of twist rate . I was told fast twist but
research on another site (Greybeard) this serial #BSS 00024 exact gun it says 1-48 ,my problem is education (high school) done .Most times no problem to determine twist rate ,BUT the rod goes 17.5 inch that"s it ! I get exactly 12 inch =/1/4 turn and then the final 5.5 inch it clears the barrel/not quite another 1/4 turn SO what do I have other than a lack of math skills . Did not shoot great with 490/495 RB /did okay with lubed Great Plains and best with S+W 501 sized to .499 w/ 2 wraps 9Lb group /Johnson 1942 made a custom 45 cal boolit that I shot fairly well (10 shot)while at the range.