There was the more common 50/110 (50 Ex) and, as you mention, the faster twist 50/100, the latter being loaded with a 450gr bullet - both used the same 2.40” length case. There is some evidence that Winchester dabbled with an intermediate 105gr BP loading using the same length case, but that one seems to be more a prototype / experimental loading.
The original 50/110 had a twist rate of 1 in 54” but I’m not sure about the 50/100 twist rate.
