Opposite....Theoretically a .680 will throw a tighter pattern than a .695,Usually a larger # means the choke is more open,and will throw a looser pattern,but Hear me out...
The 835 is a 12ga barrel that isbored out to a 10ga.Basically a 10ga barrel that is chambered for 12 ga shells.
There is a difference between overbored,and backbored.A 10 ga is .775.The 835 mossberg is.775 it is overbored.A "Backbored barrel" is a 12ga bored out to .740-.742.Such as WInchester SX2,SX3,and brownings that use the invector+ system to name a few.
The 12 ga is.729-.731.Those are the cylinder sizes.Therefore the 835 uses a looser choke,and acheives the same results.For example an HS undertaker choke designed for Hevi is .675 for the 12 ga,and .705 for the 835 back bored gun.That means .775-.705=.070 constriction.The smaller thechoke is than the barrels cylinder...the tighter the choke is.Therefore usually holds a tighter pattern for longer distances.
You want to use as tight of choke as you can without blowing the pattern.If you get too many pellets trying to squeeze through the hole they will flat side,and you will get more flyers.Generally you can shoot a tighter choke with smaller sized shot.Depending on what size shot you have...Will determine what size constriction would be a better starting point.
For the 835 shooting #4's I would use a .685 .For shooting #5's or#6's I would go with .680,or even as tight as .670,but would advise #6's if you go that tight.
Shooting hevi-shot?Hevi-shot is harder than lead and shouldn't be compressed as much.That's why it shoots better(generally)through a looser choke.I would say go with the .705,or if you want to shoot nitro loads you can get the rhino which is .695,and that is fine B/C Nitro is mostly small #7's anyways,so you can get away with a tighter choke.
Also You can't shoot slugs in your 835,because it isn't the proper bore.The slug may wobble,and can cause damage.Just thought I would throw that in there for refrence purposes.
Hope I helped.