I'm looking at this Remington 870 20g 18" Knoxx Package




Any cons to this for hunting or self defense?

Just off the top of my head without digging into ballistics info from what I have learned before I bought my 20 for bird hunting, just a few less pellets per load and as far as power it might only be lethal out to 40 yards instead of 50-55 with a 12.

Tacticly a box of 20 is a bit lighter than 12, smaller easier to handle.

A con may be that 12 is sort of the norm so in a SHTF situation 20 will be less prevalent.

ETA: Trench Coats look cool.

You'll find some good shotgun info in the shotgun section:

www.ar15.com/forums/forum.html?b=6&f=1

I hate that all those telescoping stock adapters don't fit flush
good spot to get hung on stuff

It'll sort of suck for bird hunting if that is what you are going to use it for.  A regular express with a short barrel, a vent. rib and bead will probably suit both of your purposes better.