Look at the pictures I posted above of the 590A1 18.5" and the 500 Tactical Breacher shotguns. You can see the barrel lug ring is the same as on your 835.
Don't confuse the Mossberg 500 Tactical Breacher shotguns with the standard 500 shotguns. They are not the same.
The standard Mossberg 500 barrels will not fit the 835 because they have a different mag tube setup. The 835, 500 Tactical Breacher, 500 MilsGun (Special Military shotgun) and the 590A1 with a 18.5" barrel only, not the 20" barrel 590, have the same mag tube setup so the barrels and mag tube extensions will interchange.
The 835 has a 3.5" chamber.
The 590A1 18.5" and 500 Tactical breacher barrels have a 3" chamber. If you install one on a 835 you can't shoot 3.5" shells out of it, only 2 3/4" & 3" shells.
GC