Are the internal parts the same as a H&R? I had the same problem on a Handi rifle that I cured by making a new trigger extension that holds the transfer bar in position slightly higher and longer.
Edit:
I took a look at RD's trigger thread and borrowed one of his pics. The Rossi trigger extension looks a lot like the H&R one.
So what I did was to make a new part. I added about .060 to faces A, B, and maybe C. I then assembled the parts outside of the receiver using the pins and holes, but no springs. I then filed the faces A, B, and maybe C until it would cock. I think I ended up with face A about .030 longer and the other two somewhat less. (Sorry about the "maybe C" part, but I really can't remember if I lengthened that face.)
This ended up holding the transfer bar up higher and longer. The transfer bar absolutely will not retract until I release the trigger. I now have solid primer strikes and 100% reliable ignition.
I think I made the part out of .050 mild steel. I figure it will hold up as long as the other junk steel H&R parts.
Hopefully this helps. When you get a misfire have you checked to see if the transfer bar is up until you release the trigger?
![Image](http://i424.photobucket.com/albums/pp330/305178/rossi%20trigger_zpsgxf8tniq.jpg)