There are 44 missions total in "The Secret Armory of General Knoxx":

Scooter? But I Don't Even Know Her.

Big Crimson Brother is Watching

Wanted: Dead!

Boost the Monster

Core Collection

Greasemonkey

You've Got Moxxi: Roadblock

You've Got Moxxi: Moxxi's Red Light

Prison Break: Road Warrior

Road Rage

Power Leech

OMG APC

Prison Break: Over the Wall

Claptrap Rescue: Lockdown Palace

Prison Break: Try Not to Get Shanked

Rendezvous

This Bitch is Payback

Code Breaker: Analysis

Code Breaker: Time is Bullets

Athena Set Up Us The Bomb

Drifter Lifter

Knoxxed Out

Bridging the Gap

This Bitch is Payback, pt. 2

Bugged

Stain Removal

Thrown for a Loop

Lost Lewts

Armory Assault

Loot Larceny

You. Will. Die.

Circle of Duty: New Recruit

Circle of Duty: Cadet

Circle of Duty: Private

Circle of Duty: Corporal

Circle of Duty: Sergeant

Circle of Duty: Medal of Duty

Mop Up

Super-Marcus Sweep

Local Trouble

It's Like Christmas!

Thirsty the Midget

• Purple Juice!
  • Little People, Big Experiments

Red Loot Crate in Road's End

• Lost Lewts