Had the same problem with my model 12 Doc. Ramp would just fall down into the mag well. I just used a trial and error combination of a piece of wood and foam rubber in the bottom of the well until I got the tension I wanted. Been working fine for about 9 months.

Another thing I did for single shot firing was to remove the ejector. I find it quite handy not having to catch empties with the off hand or look for them off the bench.