When I was learning to shoot double triggers, I had the same problem. I used a piece of mini-cell foam (commonly used in boating , a fairly stiff, gray foam, doesn't soak up water) and attached it with a small zip tie. This worked well to keep my finger from getting bashed till I learned how to shoot a straight stock better. One older friend of mine had the same problem after some health issues. He had a gunsmith extend the trigger guard so that it was at a much lower angle and basically met the finger where it grasped the stock. Didn't cost a whole lot as I remember and seemed to work well. Good luck.