Where you find your differences mainly are foreign vs domestic thread sizes and how deep in the receiver they tap. A Marlin 336 screw vs. a Remington 700 screw could have 1/8 to 5/32" length difference and if your erred on the long side by 1/16 it could have enough slop to change impact each shot but not enough for you to find without trial and error changing.
Being a "QC" guy by trade, THIS was exactly the kind of answer I was looking for, with regard to the question of screw depth that came up during this thread topic. Thanks!!
"If the river sounds; somethings coming"