Starline finally did a run on the 38-55 2.125" brass and 500 of them arrived on my Doorstep
I tried to bump it up to 1,000 but they didn't have the inventory...
Starline 2.125 and Winchester 38-55 brass
Right out of the box
Side by side comparison
The Lee 379-250 RF shoots very well in both W's and my 336 Cowboys. With the Winchester brass the Lee bullet must be sized to .379" in order to cycle into W's and mine will cycle them as cast. His shoots the .379" sized bullets very well and mine has a definite preference for the larger as cast variety.
Lee bullet as cast
The as cast Lee bullet in Starline Brass wide dimension is .395" Loaded with the (excellent) RCBS Cowboy dies, crimping die set ~5/8 of a turn past touching.
The Winchester brass loaded with an as cast Lee Bullet. This round will cycle easily through my CB but NOT W's. With the Starline brass and the fatter as cast bullet it will cycle easily in his rifle.
The OAL for the Lee bullet in the Starline 38-55 2.125" case is 2.530" using all of the crimp groove. It cycles flawlessly through my CB. Comparatively the OAL I've been using with the Winchester/Lee combo is 2.500"
A 2.550" OAL will cycle through the Marlin 336 Cowboy's chamber.
In tests over the chronograph there have been no appreciable differences in velocity between the Starline and Winchester Brass. Accuracy too seems to be unaffected.