Demolition ranch on youtube has a certain amount of silly fun shooting things with various calibers of rifle. The have also investigated Tannerite to some extent. FPSRussian on youtube is a similar nut, he has calmed down since a chunck of car door almost got him though. There is a bulletinboard/ site like this called the High Road, and they have a box of truth as a reference. Watching several hours of all that will give you a sense of ballistics, like how much paper it takes to stop a .50 BMG round.
Setting up ballistic barriers like flowerbeds is a discrete way to go, and from those and some other sites I have looked at I remember a rule of thumb. 1 foot thick of 3/4 inch sized crushed, and compacted, aggregate can stop most rifle rounds. If you find a durable containment for that, you now have a durable ballistic barrier. The problem is, that can provide shelter for home invaders as well, so plan carefully. Planters right up against the house where you have the abillity to shoot people hiding behind them is a good concept.....
Rammed earth is also a good barrier, I know there are bags made for that application. What you put in those bags is invisible and you can stucco over them. There are many Earthship and Rammed Earth homes being DIY'd on youtube. I have several rammed earthbag retaining walls on the gulch that were salvaged from some recent cleanups, I mixed in local gulch dry clay with salvaged cement on those walls. They are not going anywhere given the vertical rebar driven thru the bags when they were still wet and the tie backs from the wall I made with rebar hooked around those vertical ties. the rebar going back into the hill is encased in cement filled earthbag. This same technique could be used to make the walls of an earth sheltered house. If you want ballistic protection that is durable, forget about the planters and build a second, hidden and off the record, basement under your house with the money you save. Maybe fortify a couple of points inside your house to cover your retreat. Your whole house in a real SHTF situation becomes camouflage and the looters can have the big screen TV, or burn the house down for all you care.
If you are talking about armor you can walk around in, a plate carrier and ar500 plate backed by a levelIIIa vest is as good as it gets and generally only covers the torso. The kevlar IIIa vest is going to give you protection from casual knife attack, slash and snap cuts from a knife. A solid stab with something other than a kitchen knife will probably get you. If you want real protection from cutting threats, learn to make chainmail and cover the exposed artery areas with it, and add it to your arms so you have a real defense from cutting too.
