I am not sure about the diagram,but I would check at numrich gun parts corp. first for the parts you need.
i need a diagram of the internal parts of this gun. where would i find it..
On www.FirearmsGuide.com
Try e-gunpartsl.com
In America, we contact the manufacturer directly. They are often willing to share information regarding their products gratis.
www.gunstockinc.com
Contact Customer Service for Savage Firearms. They have owned the Stevens name since the 1920's.
I have a fairly complete selection of parts for this model. repair@countrygunsmith.net
You can purchase parts for a Ranger model 30 16 gauge shotgun at these locations. Gunbroker, Topgunsupply, Budsgunshop, Gunpartshop and Midwayusa.
J.C. Higgins is an old brand name used by Sears.
Send me your email & I'll send you a scan of the diagram. USDF
Numrich gun parts