I'm trying to install replacement factory iron sights on my Marlin 336W, but am having trouble fitting it. Not sure if I need to do some more filing or just need to keep tapping it and force it in there. Any gunsmiths out there have any advice on how to make it fit in flat and not crooked? Which side of the sight should I file? The bottom part of the triangle, or the right side in which it's having trouble fitting in?