Went shooting today. My 835 Ulti Mag, 3.5" ported 28" 10 gauge barrel, decently used. A friends Remington 870 Express Super Magnum, 3.5", 28" barrel, nearly new.
Put about 100 rounds through each, including 3.5" steel shot. 4 people who had very little experience with shotguns and one who had never fired a gun before.
My ran flawlessly with everything and everyone liked shooting it more, less recoil as it is heavier and ported and the safety was much easier to use. Only issue the group had was it was heavy.
The 870 ran flawlessly except it will not always eject the 3.5" shells and sometimes had to FORCE it to cycle, did not matter what ammo. The issue was recoil.
This is just one 835 and one 870, I believe most of the cycling issues are because maybe the Rem is just not broken it, but the chamber might be a touch to short. Although with just a few hundred rounds the marine coat finish, or whatever Rem calls it, was already starting to wear, while my old Mossy with bluing, I prefer the Marine coat, was only worn at the muzzle and slide area, only showing a little blue.