As I cleaned a mossberg 500 today, I decided to take photos step by step throughout the entire process. Here are those photos with explanations for each step of the process.
Put safety on, Check to make sure firearm is unloaded, Pump forarm back and forth, Double check to make sure firearm is unloaded! , pull forearm back 1/2 way and remove barrel,
remove trigger guard retaining pin [ located bottom rear of receiver],
remove trigger group [pull up on rear of trigger guard and pull trigger group rearward],
remove cartridge stops,
remove bolt slide plate,
push forearm forward and off ammo tube,
remove cartridge elevator [squeeze rear of elevator until pins pop out of holes in each side of receiver, then lift out] ,
remove bolt body[ slide forward and out barrel hole in front of receiver].
Receiver is now empty and ready for cleaning.
Insert bolt through barrel hole in front of receiver, with extractors forward,
install cartridge elevator, [squeeze together and insert pins into mating holes]
Push front of cartridge elevator down onto bolt body,
slide forearm onto ammunition tube and slide end of action bar into mating slot on receiver [push end of action bar toward top of receiver and slide toward rear of firearm to insert action bar into receiver]
Install bolt slide plate into receiver, lining it up on top of action bar and into bolt body [this is a bit tricky so make sure the action bar , bolt slide plate and bolt body mate perfectly , you may need to wiggle all three around a bit. The bolt slide plate will only drop into the receiver in the bolt slide plate cut out area.]
Install cartridge stops, [The one on the side of the ammo ejection port is the smaller of the two, it is also the one with the pin that inserts into the mating hole in the receiver , the larger of the two installs on the solid side of the receiver. Both install hooked end inward]
install trigger group [while holding cartridge stops in place install trigger group, front in first then snap trigger group down in rear]
install trigger guard pin,
Firearm should now be reassembled and ready for function test.