Bottom line on ammo/gun problems in ANY firearm, rifle, pistol, or shotgun is:
Not all guns "like" all ammo.
Different guns produce different reliability and accuracy results with different ammo.
This is even more so when using cheap, off-brand foreign ammo.
You may have two guns of the exact same make and model, with close production dates, and it's not unusual for one to give radically different results than the other.
Since your 870 doesn't "like" S&B ammo, this is like the old joke: "Then don't shoot that ammo".