Ruger used to offer checkered wood inserts made by W.H. Lett Grips for the "canoe paddle" stocks (along with inserts for the GP100, SP101, Super Redhawk, etc) but they are long gone from the catalog since they dropped that style stock in '99 or thereabouts. You might scrounge up a set on ebay or one of the other gun auction sites, but I kinda doubt it anymore. I don't know of anyone still making inserts for that stock anymore, rubber or wood.
The grip panels aren't that hard to make if you're a fairly handy woodworker. Checkering is the hardest part of that task. I started a set for my 77/22 many years ago, but they got back-burnered until I take the time to brush up on my checkering skills.
I suppose you could checker the original rubber inserts too. Might look kinda funky checkering over the existing grooves but it would help with the grip.
Another thing might be to clean up the inserts good and apply some grip tape or even coat em with a non-skid marine "grip paint" used for painting those grip treads on docks, boats, etc.
I love the two canoe-paddle stocked rifles that I've got and I don't have any issues with em, but honestly if you want a good non-slip all-weather hunting stock I would suggest checking into a Hogue Overmolded stock and replace the entire stock.
The Hogue stocks are nearly as solid feeling as the canoe-paddle stocks and are tons better quality than the synthetic stocks Ruger is using these days.
