Remington 870 Complete Mcs System Remington 870 Slug Barrel - Is There Any Harm In Shooting Reg Shot Shells With It?

Remington 870 slug barrel - Is there any harm in shooting reg shot shells with it? - remington 870 complete mcs system

I bought a Remington 870 Express, and I am looking for additional barrels, like, leave the gun, if they do not hunt birds. I doubt they hunt deer with it, but a 20 "barrel would be about normal.