I've made 3 custom weapons, 2 .45 Auto Pistol (one silenced) and a hunting rifle, all of which use new meshes, well when I say new I mean I extracted them from the games .bsa files because I wanted vanilla weapons with mods, without needing to manualy put the mods on.
I got the meshes from the Honest Hearts - Main.bsa and Fallout - Meshes.bsa and put them into the meshes folder:

meshes/weapons/2handrifle (for the hunting rifle mesh)
meshes/weapons/nvdlc02/weapons/1handpistol (for the .45 Auto Pistol)

The meshes I extracted are:

huntingrifleallmods.nif (Hunting Rifle with Scope, Custom Action and Extended Mags)
nvdlc02weap45autopist2.nif (this is the standed .45 Auto Pistol, didn't really need this one)
nvdlc02weap45autopist12.nif (.45 Auto Pistol with Silencer)

The point is, I did all this but the weapons in-game don't have the meshes I chose, wether this is because the game can't find the meshes where I put them or something else I don't know. basicly, is there anything I'm doing wrong and if how can I fix it.

Thanks.