Howdy YooperJ,
When I started Cowboy Action Shooting with a SXS and double triggers, I had the same problem. We shoot as fast as we can, from different angles and positions, and cannot always get our hands in the proper places to avoid getting your middle finger battered and bruised.
The first thing that I tried, was some tubular foam padding that you can get from the pharmacy or medical supply store. It comes in a long length, and the store will either sell you a whole box, or usually cut you whatever length you need. You cut an inch or so and slip it on your finger down to the last joint. Sometimes I added a layer of adhesive tape to make it a little sturdier. That worked for a while, but eventually I found out that......
what I needed was more length of pull (LOP). I added a lace on pad to my SG, which moved my hand back an inch or so, and voila, the problem was solved. No more banged up finger. No more bruises. No more ouch!
Happy trails,
HHH