I really don't know the true difference other than the 535's forearm is shaped more like that of the Remington 870 at least to me it does....but I don't think that the 535 shoots 3 1/2 inch loads like the 835...they make a 935 autoloading shotgun that shoots the long shell too... as for weapon of choice for turkey's....I would go with the 835....it's just a jam up gun that get the job done...almost bought one this past year but decided that my 870 3 inch was getting the job done good enough... but yea I would go with the 835 that way if you decide to shoot a 3 1/2 inch load you will have a gun that will do it... although you really don't need it for turkey...my 3inch will outshoot my dad's 3 1/2 anytime....but it's all in the choke and load also...
