I have enjoyed owning my old Mossberg 500. I swapped out the 28" barrel for a 18.5" security barrel. I swapped the wood furniture out for plastic furniture with a full buttstock featuring a pistol grip for better control. I added a shell holder on the receiver (like 2 screws in existing holes, very easy). I tried the heatshield with the ghost ring sights & didn't care for it. I tried a sling and didn't like it enough to keep it. It is beside the alarm clock.
I kept all the original bits in case i want to go dove hunting with it.
SHT-003 - Side Saddle Fits Mossberg 500 or 590 or 600 Shotguns Holds Six Shells no Gunsmithing
I bleve this is the shell holder i use.
This is the butstock i use, with a matching forestock.