I'm talking here about an 870 tactical, not a hunting 870. i.e. sidesaddle, ghost ring nightsights or RDS or both, tube extension, mounted tactical light, etc.
Use: Home defense, SHTF at home, multi-role situations.
Of course the M4 is a semi, the 870 a pump. The 870 is time tested and proven, the Marines issue the M4, and having said that, you discuss, I want to listen. And of course it's rare that I can listen without commenting, but I'm gonna try.