I'm glad you asked, because more often than not, it will be the difference between getting to the throne, or dying on the next level.

Just to put the above text into perspective. What is the most hated boss fight pre-loop?
A) Random bandit shots
B) Lil Hunter
C) Guardian Dogs

If you answered (B) Lil Hunter, you are correct. Lil Hunter is the most hated, because of his devastating attacks, his phone which is always set to dial 911 and his homing post-mortem explosion.

Despite all that, there is one thing he does not have, and that's a sizeable health pool.
He can be taken out in 1-2 well aimed shots from a heavy hitting weapon like the super slugger, super crossbow, nuke launcher, assault slugger, heavy slugger among others.

When picking your loadout, always plan ahead.

Like I pointed out in the example for Lil Hunter, picking the right weapons for the situation will give you an edge, if not win you the game.

A wrench or shotgun will do good in a the sewers, but without scarier face that wrench can't one shot a raven in the next level.

Having a melee weapon to destroy projectiles on the throne fight is invaluable, especially if RNG is not on your side (I'm looking at you all-ball throne).

Running with two slow firing weapons will put you in a situation where taking damage is inevitable or even outright kill you.

Always have a fast firing weapon and a hard hitting weapon in your loadout, that way you are safe and have that burst damage to take out tougher foes.

It is important to take a mental (or real) note of what killed you, so you don't make the same mistakes again.

Knowing what weapons are good for the situation is all fine and dandy, but what happens when you can't use your weapons to their full potential?

Anyone can walk into a crowd and press the LMB.
But here are some things you may not know about your weapons.

Fast firing bullet weapons have a stun/knockback effect on enemies, keeping things like big maggots, rats, assassins or even big dog from charging you. Bouncer weapons will do an extra point of damage for the same amount of ammo.

Shell weapons get bonus damage from close range, which includes those that bounce off of walls making them the best for cleaning out corridors and tight spaces. Sluggers are some of the harder hitting single target weapons in the game.

Bolt weapons will give you some crazy multi kills with scarier face and bolt marrow while staying efficient throughout, but remember that there are 3 levels of bolt homing, from lowest to highest being heavy bolts, normal bolts and splinters, it also helps seekers find their target much faster.

Explosive type weapons have both AoE and impact damage, although they will end up killing you without boiling veins, those suckers scale very well later into the game and make some of the best throne killers. Mini grenade weapons also pack some juicy DPS and are relatively safe to use without boiling veins.

Lasers will pierce and kill anything that isn't a wall, including shielded IDPD, same goes for the smaller plasma firing weapons. However, using them without laser brain can be a waste of ammo later on in the game. Lightning weapons, on the other hand, will benefit much more from scarier face than they will from laser brain.

All melee weapons can hit trough walls and multihit charging enemies like big bandit and guardian dogs.

Golden weapons are slightly upgraded versions of their non-gold counterparts, the upgrades are mostly to rate of fire and accuracy with some weapons like the shotgun and splinter gun firing an additional pellet or splinter.

There are over 100 weapons in this game, and you are not going to find a gattling slugger, auto crossbow or energy sword to carry you on every run.

There are plenty of ways to get better weapons faster, like playing robot, getting crown of curses, every additional portal you go trough will increase the difficulty and give you better tech, that includes crown vaults and the turtle level.

One method I will encourage you to use today is skipping chests.
Yes it doesn't always pay off, but neither does opening every chest you see.
If we do the simple math, every chest you skip adds 25% chance to find a big chest, so worst case scenario, you get one less weapon than you would have opening all the chests.

Trust me when I say, you are not going to get anything amazing in 1-3 after you get an assault rifle and crossbow combo in 1-2. The only exception to that would be if you're running CoC (Crown of Curses), since you can't get a cursed big chest outside of the cursed caves.

Besides the obvious weapon specific mutations, there are other mutations to help you (or not) along the way.

• Back Musle - Underrated by many, this mutation will always benefit fish and will benefit any run that already has good ammunition gain mutations, even though you will be stockpiling ammo for weapon types you don't use regardless of your other mutations.
  
  
• Heavy Heart - Not a mutation you see in your regular mutation pool, because it only shows up once and only after you choose your third weapon specific mutation, I would not recommend taking 3 mutations of that type, simply because you can only carry 2 weapons. But if you want to swim in weapons like our friend fish up there, then go wild. (It's still better than Crown of Guns)
  
  
• Gamma Guts - Especially when paired with scarier face, it helps loads with cleaning out small enemies when you are out of ammo or simply do not wish to waste any.
  
  
• Impact Wrists - Just like gamma guts it helps clear a level from small enemies and conserving ammo along the way.
  
  
• Scarier Face - Works well with bullet, lightning, and shotgun weapons, it's the only mutation that makes low tier weaponry more viable and helps a ton when taking on bosses and high health enemies.
  
  
• Trigger Fingers - Opens a whole new world of big, mean and highly ammo consuming guns, a must-have for many of the slow weapons like shotguns, supers and cannons.
  
  
• Stress - It's one of those mutations that is nice to have, especially when facing a boss or tough spawn, as it makes even the machinegun look good. Be warned when taking this mutation as it can leave you without any ammo in no time.
  
  
• Open Mind - Will help you with both ammo and guns, getting those big chests much faster. Works with Crown of Love, providing you with more ammo chests once you have your optimal loadout.
  
  
• Eagle Eyes - The most situational mutation in the game. For what it does, it destroys way too many weapons to be useful.

Both ammo and weapons can drop from enemies, it is important to know which enemies to focus when you are running low on ammo, in this section I will be listing the enemies with information about their drops.

Note that the information below does not factor in crowns.
* = Indicates this enemy can be farmed for ammo.

(1-1 to 1-3)

(2-1)

(3-1 to 3-3)

(4-1)

(5-1 to 5-3)

(6-1)

(7-1 to 7-3)

There are some rules to keep in mind, if you want to be a gun god.

• Bullets are of no use to the dead. (if you're in a sticky situation, just unload)
  
• Your ammo is your life. (starting a level with an empty weapon can kill you)
  
• Upgrades, upgrades, upgrades (having bolt marrow is a bad excuse to take a regular crossbow into 7-1)

This guide has been getting a lot of positive attention. If you guys and gals want another guide on how I do well and have fun in late game, let me know by leaving a comment.
I would be glad to share my 800 hours of experience.