Are you referring to the trigger stud when you say trigger pin.???
The trigger stud and hammer stud are both a press fit and are probably the most difficult part to replace on a S & W revolver. You need a very good press and inserts to do the job. I did several back in the late 80`s and if I recall even S&W state you will have a 10% or so failure rate as sometimes the frame will give way around the stud hole even with frame side supports.
When the stud breaks free it goes with a bang and I just about fainted when this happened on the first one I did. A new stud is then pressed back in and then filed/polished flush then reblued. Not an easy task and I would not even hazard a guess as to cost.
I do not have the tooling as I worked for the province when I did these. MD Charlton should be able to replace the trigger stud but I do not think any one else can. I wish I could be more helpfull with your problem.
S&W could fix you up if you could find a way to get your frame back to Springfield Mass.
khornet