The 325B is a Mossberg 385k. any good shotgun gunsmith can repair it.
Inquire with a competent gunsmith.
Find a qualified gunsmith and let him/her fix it. Find a qualified gunsmith and let him/her fix it.
Find a gunsmith
You find a gunsmith.
You need to find a gunsmith.
You need to find a gunsmith.
Send it back to the maker or find a gunsmith.
Find a good gunsmith.
The eaisest way is to find a competent gunsmith.
This shotgun was probably made by Crescent, so your local gunsmith can probably find one in his parts pile. Or, if there are no missing pieces, he can repair yours.
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