I am currently a 2-3 star player running T2s, and I already have my general loadout for general PvE:(Its a sword mostly loadout)
1. Barbarous Thorn Blade (for piercing damage)
2. Glacius (for elemental damage)
3. Gran Fuast (for shadow damage)
4. ???
For the fourth weapon I want a normal damage type gun for situations like gun puppies etc, but I want it to be applicable to any level. What do guys think is the best normal only gun?
You don't actually want a normal gun. You want an elemental gun.
Gun puppies and howlitzers are weak against elemental. Polyps are neutral. So, elemental guns are the best turret killers. Beasts and gremlins dodge bullets anyway, so it doesn't matter that an elemental gun is weak against them. A normal gun will miss just as often, so you may as well do better damage to everything else.
The best elemental gun for solo play is the Polaris (kilowatt pulsar line), but the knockback from its expanded shots can make it difficult to use well in a group. Any of the elemental alchemers is also going to be good and will be more friendly to your team because there is no significant knockback from them. I particularly like the firotech line.