I have played FO3 a lot and like very much the combination of CALIBER and 20th Century Weapons.

Now I am playing FONV I wondered if some of you experienced fellows could recomend the best weapon mods and perhaps say why they are good to allow me an oportunity to decide what would be good for me.

Many thanks in advance.

http://www.newvegasnexus.com/downloads/file.php?id=39651
WMX:Weapon Mods Expanded

There's WMX (link above) and WME (http://www.newvegasnexus.com/downloads/file.php?id=37576)

I'd say look at the both mods readme, take a look at the weaponmods each mod provides and decide what you rather have. As far as I know, there really isn't that much of a significant difference between the two beyond that.
Be sure to pick up this regardless of which one you pick: http://www.newvegasnexus.com/downloads/file.php?id=44515

Thank you both I will be looking into both of those to see which best fits my preferences.