For an all-around gun-
Cons
-18in Barrel is to long and unnecessary
-6.8 is expensive and unnecessary
-Vltor Upper while being high quality, is heavy and unnecessary
What you described is really a specialized gun.
You mentioned using it for SD/HD. If you hadn't then it's just whatever you want. If you think you may have it for serious use then there are certain things you will want.
If you buy a single high-end AR-15 with HD/SD in mind, I would like you to think about the following. I happen to live in a subdivision and my wife and I have several children of various ages living at home. When an HD situation arises and you pull out that big ole AR-15, release the bolt to load the first round off the 30 round mag and start blasting away, just remember this, you have to account and explain every bullet that you will be sending out of your fancy schamcy AR-15 and this may very well happen in a court of law in front of a judge and a hand-picked jury. If your bullets go through the interior and exterior walls or doors or windows (and they surely can,) they will continue on looking to spend themselves somewhere. For non-TEOTWAWKI situations, a shotgun or a handgun is better suited for HD. Also, I have never been able to conceal carry an AR-15.
On the other hand I read where Isaac said a few times that he wants to use this rifle for hunting and big boars where mentioned. I suspect there will also be some target shooting and some plinking, perhaps some varmint shooting, these things usually indicate a need for an accurate rifle. Longer barrels will produce higher velocity, a good thing for hunting and longer distance shooting.
Stay with tier on manufactures-Colt, LMT, Noveske, etc., or a really good "smith" that uses tier one parts. S&W also makes a pretty good gun. Forget Bushmaster, DPMS, Rock River, Olympic, etc. for serious use. They have to many problems.
Bushmaster, DPMS and Rock River are all fine. I do not believe Isaac is going into combat. I am partial to ArmaLite, there are many others.
Make sure you get a barrel that is chambered in 5.56 with a 1-7 or 1-8 twist, do not get one with a 223 chamber. 1 in 7 or 1 in 8 twist will shoot light bullets just fine, and will stabilize 77gr OTM's which do make a difference at range. Make sure it has a chrome lined chamber and bore. You're not using it for High Power matches- a 5.56 chamber and fully chrome lined barrel will help make sure it works, and as long as you get a good quality barrel you will not have a problem averaging 1MOA with match ammo.
You can also use a good stainless barrel with a Wylde or MK262 match chamber, but you do give up some longevity and durability, and reliabilty with certain types of ammo with them.
Oh my gosh, I don't have fully (or partially) chromed lined barrels in my ARs. I have stainless steel barrels and I take good care of them. I would love to know how I am giving up "some longevity and durability, and reliabilty with certain types of ammo with them."
An 18-20in barrel is unnecessary. It decreases maneuverability, adds weight and aids very little in mid range shooting. A 16in barreled gun is fully capable of shooting and hitting at mid range (5-600yds), and is much better for running and gunning.
As you probably guess by now, I like 20inch or longer barrels. Then again, I don't run and gun and as I explained earlier, I will not be using an AR for HD, unless there is nothing more suitable left.
Use a free-float handguard.
Indeed, and I explained that in my earlier posting.
In general stay away from "match" triggers. If you shoot a lot and/or attend a training class, and you should, they will fail. The exceptions to this are the Gesielle and the AR Gold, though the utility of a 2lb trigger in self protection is debatable.
I hope by now that I have made my point about how bad an idea it is to use an AR-15 for home or self-defence in non-TEOTWAWKI situations.
The stock AR-15 is actually a pretty lousy device designed to make it difficult to shoot accurately ; the trigger is designed for a full auto rifle. If you are serious about wanting to shoot it accurately, you need to change the triggers. The NM triggers from ArmaLite and others are very good. I have Geissele triggers in mine. Don't worry, they have been backordered for many months now; the government is seemingly buying all the triggers Bill Geissele can make at home. I know of none other as good, let alone better than Geissele.
Once you have fired a stock AR-15 trigger and then try out a Geissele or even an NM from ArmaLite or RRA, you will understand why you do not want the stock trigger.
As to optics- they can be whatever you prefer. All-around means from contact distance to mid range (0-500yds or so) however in real life the mass majority of use is probably going to be under 200yds. So a suitable red-dot (Aimpoint) especially with a magnifier or a low power variable (1-4x, 1.5-5, etc.) is going to be the most useful.
Get a flat top and then get a nice variable scope. There are many excellent scopes to choose from.
There is actually a name for this type of rifle and it was started by military SOF. It's called a Recce, and they work very well at a whole bunch of tasks.
Especially if you are in the military or just want to have a tacticool rifle.
