IIRC the 835 was built on a bigger frame than other 12 ga shotguns. And the OD of the barrels were a little larger than typical 12 ga barrels. I don't think it was sized to duplicate true 10 ga dimensions, but did somewhat split the difference. They are heavy cumbersome guns. The barrels were back bored for the 3 1/2" shells, which required larger diameter barrels. The back boring helped develop better patterns with the 3 1/2" shells . No, a 3 1/2" 12 won't match a 10 ga. But was close enough for most people.
Both shot shells and rifle ammo has improved dramatically in the last 30 years. Hunters are finding that smaller gauges and calibers are now capable of doing what larger ones were once needed for. I don't see the need for a 10 ga to ever make a comeback. For that matter most folks are finding that even the 3 1/2" 12 ga shells are unnecessary. For what I hunt I've never felt the need for anything bigger than a 3" 12 ga shell, and then only in rare situations.