I've recently liberated myself on the fact that I probably won't be able to get to my Ak-47 if someone breaks into my house. Being lazy like I am, I'd rather just get another rifle, to double my chances of survival in case I'm attacked. I have the brutal 7.62X39mm shells in my AK, which will shoot through 16 inches of hardened pine, but what I don't have is the light-weight, smaller, more precise, higher velocity .223 shells, that I would want to maybe just take out a potential criminal's arms or legs with. So the question is, what's the best M-4 for a $1000 budget?
And I know everyone always says "well it depends on the situation, and what you want from the gun", so the situation and demands would be:
Let's say I'm expecting quite a few (5-7) armed unwanted guests and they don't have the best intentions in mind as far as my health is concerned. I want a rifle that is reliable, light-weight, and has very little recoil. One that can dump 5 rounds into a 4-5" pattern at 30 yards during rapid fire, and still be able to tuck around corners with.

What I think I'm looking for is a Colt M4 Carbine with a very nice muzzle brake. However this far exceeds my spending limit.
I've been looking at Rock River Arms M4's and they seem like a good package for the price, having the shortest barrels, (from what I've heard about 'new' M4's)-the best looking nic-free finish, and the lowest price while still widely referred to as "right up there with Bushmaster and Colt."

Should I go with the Rock River?

And #2, Rock River doesn't have a threaded barrel I don't think, so where/how do I get an adapter, threads on the end? I think .5X82 is what I njeed for most silencers/muzzle brakes/ suppressors.
I really appreciate any feedback.