Numrich gun parts corp.should be able to help you.They may be found on the web.
www.gunstockinc.com
Have you tried e-gunparts.com?
Try e-gunparts.com
the value of a 1948 Stevens double barrel shotgun 16 gauge. Hammerless.
Take it to a qualified gunsmith to find out for sure. Sounds like it could be a problem with an extractor or spring.
NUMRICH.com
The Stevens 311 is a double barrel shotgun.
take the trigger out and read right inside of the hole.
Under trigger
Try your local gunsmith. The Riverside is a Stevens shotgun. If you can find out which model it is, you can probably find the wood at Numrich Gunparts
it is a Stevens, parts are interchangeable...
I can't find production dates for a model 357, but if it is marked J Stevens Arms Co (NOT J. Stevens and Co or J. Stevens Arms & Tool Co), the gun was made no earlier than 1920 and before 1950.