From the "Levergun Insanity" thread:
"You can run a Remington 870 as hard as you want (I run right around 1/4 second splits with one) and it will put up with a whole lot of that and eventually it will break something that you have to repair. You run a lever gun too hard once and that thing immediately stops working." (TCinVA)
Given the popularity and durability of pump-action shotguns in the US, why have there been no successful pump-action rifles other than the gallery .22s? The Remington 760 and 7600 never seem to have gained a following.