some folks will argue about anything!
I'm on the fence. M4 sounds great, but in the heat of battle, the scatter gun might be awesome. I'm thinking a 'better' shotty (Saiga) with a mix of slugs and buckshot would work perfectly. If they are in a group, having a 'area target' may prove to end the threat from multiple warriors using only one shell. Plus, I think I could find a way to re-load the shells with materials of the time - much easier than having to try and re-load brass/rifle ammo.