So, in a wood stock I'd drill out the stripped area, glue in a dowel and make a new hole. What would you do to correct a polymer stock with stripped out screw holes? Jb weld, let it set, then screw them into the narrowed channels? Pack holes full of jb weld, drill new holes, then reinstall screws? Not sure if there is a better solution someone would recommend. Regular 2-part epoxy maybe?

2 Part epoxy for plastic.  That stuff it pretty indestructible.

Do you have the proper screws . Wood screws are different threads.

My first thought was JB Weld

JB Weld has several products which could work

I've found the best-easiest method is to pack a little high grade epoxy into the holes.
JB Weld is just a higher grade epoxy with some powdered metal content.

Apply some wax or grease on the screws to serve as a release agent and prevent gluing the screws in, then turn them into the holes until they're just about to start stripping or just rotating, then allow the epoxy to cure a few hours.
Save some of the excess and when it's the consistency of hard rubber remove the screws and clean up any epoxy that oozed out of the holes.
Allow it to fully cure and you have a permanent fix.

Key is in getting a perfect mix of the epoxy components.
I recommend Johnson's Paste Wax in big yellow cans from any hardware store and most Walmart's.
It makes a great release agent and is used for many gun related purposes like preserving holsters.

EZ Lok inserts or similar would be what I would consider a proper repair. Drill out the existing hole to the appropriate diameter for the insert, press in the brass insert, install screw. As the screws go into the insert, the insert flares out, gripping the plastic. They’re cheap enough.

I tapped the hogged out holes for some nylon screws that I had.  JB welded the screws in and chiseled the head off flush.  Drilled for new screws and it worked like a charm.