I recently acquired a well used,but good condition, model 47.
The hammer is seldom retained in the cocked position when cycling the action. The hammer can be cocked and locked manually,and properly discharged. I suspect DST adjustment to be the problem,  if not, sear engagement. Please inform me of proper DST adjustment procedure. Any other thoughts will be appreciated.

In adjusting the trigger loosen the screw in-between the two triggers. Set the back trigger and you then want to start screwing  the screw back as you are watching the front trigger moving back as you do. When that movement stops you are pretty much there but you can trying going both in a bit more or back out a bit until it's to your liking. If you go in to far the back trigger will no longer set so just back the screw out and repeat the process. Also keep in mind the hammer typicaly needs to be in half cock for the back trigger to be able to set. You can also set it and touch the front trigger to see how it releases as many times as you would like without having to put the hammer into full cock. 

JLouis

If your back trigger seems a bit to hard to set you can back off the flat spring pressure that applies the down force to it by simply backing out the screw that attaches that spring. 

JLouis