People may already know this one, but if not, then here is a trick for anyone with a Mossberg 500/590 shotgun who wants to know how to remove shells from the tube magazine without cycling the action”
Inside the loading port located on the left is a small piece of metal [called a shell stop] which holds the shells in the magazine (it’s easy to see with a shell in the magazine). Pushing this in allows shells to be removed from the magazine one-by-one swiftly and silently. Push the piece in until a shell pops out of the magazine, release the metal piece, repeat. I use this trick during hunting season to unload my shotgun for transportation purposes. It takes some practice, but it works well on low/high brass shells. It sure beats having to pointlessly manipulate the action and damage the rims of shotshells by doing so.
Respectfully Yours, – D. from Michigan