Try e-gunparts.com, gun shop, gun shows, want ads.
You can purchase parts for a Ranger model 30 16 gauge shotgun at these locations. Gunbroker, Topgunsupply, Budsgunshop, Gunpartshop and Midwayusa.
You can find parts for many westernfield shotguns at Numrich gun parts. WWW.e-gunparts.com
I would start my search at Numrich Gun Parts Corp.
Go to Cheaperthandirt.com
Depends on the model. We usually have parts.
Folsom was a brand name used by the Cresent firearms company,which was in business from 1888-1932.If your shotgun has Damascus barrels then it was made from 1888-1900.If it shoots standard smokeless powder shells,then it was made from 1901-1932.
The 238 is similar to the 258. For parts, try gunpartscorp.com
Not readily. You'll find that parts will need to repaired or made by a gunsmith.
try e-gunparts.com also Cabelas.com and Gandermountain.com
You might find what you need at firstname.lastname@example.org .