You could try making a barrel or scope say for one of the vanilla weapons and try and get that ingame then once you've done that bit go from there. That's as far as I've got due to time and straining my eyes from modding! http://www.nexusmods.com/fallout4/images/17886/? You could try downloading someone elses finished standalone weapons mod and look at their .esm, that may shed some light. Sorry if that doesn't help much as far as tutorials go. The truth is out there...