Looking at reviews and specs, it does say 45-70, though as with many higher pressure cartridges, there may be some barrel length restrictions on that one.I have a 45 OBS. I just looked on the Rugged website and the do sell a 11/16x24 thread mount that fits my Ruger Trapper 45/70. I have use a Hybrid on it, but I lost the thread mount. I think I just might know the SiCO mount got off to.
Anyway, if the OBS does indeed 45/70, I will use that on it. Some of the load can get quite stout. I will call Monday an ask. The website says 450 Bushmaster and mentions most "common" lever calibers.