This one is .38-55, 1/14" twist Shilen.  CPA had an exceptionally long blank so I bought it and saved as much length as I could when I turned and chambered it.  These are a square thread, 12tpi. (if I remember correctly...) Barrel is 35.5". Manson chamber reamer.  (I have a 1926 Hendey lathe, 14" swing)

I've been experimenting with N320 powder and have been getting impressive "gangs", but "groups" are coming, hopefully to be followed by "bug holes."  I have been surprised that I'm getting single digit standard deviations, like 6.5-8.5 on 50 shot runs. I've got more work to do but I like that!