Ruger responded to my follow-up inquiry about the groove diameter:
"The measurements are .3560-.3580. Thank you for your email."
Oh well...
I'm not sure what they're indicating there, the diameter in the grove and the diameter in the field or a range of values that any particular LCR might have for its bore diameter.
By contrast, the Alfa Proj 9231 is .34724" in the field and .35512" in the groove.
Either way - the Ruger sounds like it has a larger diameter bore than the Alfa Proj.