You could get a new barrel, they are Spyder threads.
Trigger jobs are easy enough, you just have to remove the trigger from the frame and find something that will go inside the trigger return spring to reduce the amount that the trigger can be pulled back. I use to set them so as it would only just fire.
-Or-
Drill a hole in the sear, tap a hole and put a screw in it, as Adam has surgested above.
Hope this helps