As JC stated..."there are no J. Stevens serial records existing for any model and have not been since way before WW II. There are no production records either. I have a remnant of some Stevens comparison production records , but not this early and as far as I know these are the only ones that exist."
I think GeneB is correct that the production number of 11,000 for the two models might just be a combined number and not two models with one serial range. I don't see another rifle in production that had any similarity to the 425. The models that I know of that share a serial range also share parts. What Model 15 shared parts???
Based on the serial range of 425's that you have collected I think the serial range runs from 1000 to 6000, give or take. No sharing of serial range.
JMO
Savage...never say "never". Rick...
Join the NRA...together we stand, divided we fall!