Backplate slop
When I got my 1919 I had the same problem with the back plate moving up and down...When it would move down it would keep the trigger from tripping the sear , making the trigger next to imposable to work...I shimmed up the plate with some small rubber pieces and the trigger works great now...Some guys cut more clearance at the trigger slot to fix this, but I like mine shimmed because it takes away the up and down slop.
When I got my 1919 I had the same problem with the back plate moving up and down...When it would move down it would keep the trigger from tripping the sear , making the trigger next to imposable to work...I shimmed up the plate with some small rubber pieces and the trigger works great now...Some guys cut more clearance at the trigger slot to fix this, but I like mine shimmed because it takes away the up and down slop.