Tech Q, Mossy 500 Magazine caps

[Gothboy]

So I recently bought a mossy 500. It has the breacher barrel, which I think is really nice for home, but if I really want to take it out and use it I want to change barrels to something abit less "stabby"

Here's the catch. The magazine end cap seems completely different than the regular "thumbscrew" type cap that ALL the barrels I can find have. This one is actually more like a "cap" by definition.

First, why is there a difference in caps, are they all interchangable once I get the barrel off?

If they are not interchangable, then do I need to change out the magazine tube too, just to change the barrel?

Im kinda stuck here. Please advise?

[land locked]

It is a hybrid Mossberg probably a special purpose model. Does it have a pistol grip? It uses the 590 magazine, cap and breacher barrel vs the standard 500 set up. I am pretty sure a Mossberg 835 barrel would work with that configuration.