If the nose on the top face of the hammer is clipping the top edge of the transfer bar
It will cause the trigger to kick back. Due to stacking dimensions of trigger,transfer bar,frame etc. the transfer bar may be rising up too far and being cliped by the hammer nose. I would check by blackening the top edge of the transfer bar and the hammer nose with a felt marker,dry fire and check for marks. The transfer bar can be shortened a smidge if that is the problem. My best guess ???
Or hold the trigger all the way back and slowly lower the hammer with your thumb. Do you feel any catches? Or does the hammer go all the way home smoothly and the firing pin protrude from the breech face as normal?