so I emailed Mossberg about using 835 barrels and this what they said.
This is one of a few of what I call "special-case" model 500s. Normally the 500 has a takedown screw, however like you've stated yours has an open lug and magazine cap. You cannot use the 835 barrels on the 500 because the...
I have a 500A 12g https://www.turners.com/mossberg/mossberg-500a-12-gauge-185-bar-6976
and couldnt seem to find longer barrels. it has a screw cap like the 590/835 have. I'm trying to find a longer barrel I could use for trap shooting or sporting clays. I went with some co workers and enjoyed...