there is this mod on nexus called AG Supplementary Uniques . It's has a lot of custom weapons and all using only fallout NV and it's DLCs meshes and textures and if you use WME you get 2 or 3 more weapons . All of them (or a good part of them ) have they own modifications ! so here is my suggestion !
here is the link : http://www.nexusmods.com/newvegas/mods/40000/?
try it !