I have been doing a lot of research about getting a new Tactical AR-15 type rifle with an optic. I am open to different suggestions and I am seeking advice. I have never used an AR with an optic. I would like to use an Aimpoint Comp ML2 with a forward mount and I want to co-witness BUIS through it.
I was considering starting with a Rock River Arms 16" M4 Variant rifle with a flat top upper and an aluminum Quad rail handguard.

Bottom rifle in this link.
http://www.rockriverarms.com/item-detail.cfm?ID=AR1000&storeid=1&image=rcara4.gif

A Bushmaster of similar configuration would be my second choice for a base rifle.

Do I need a chrome lined bbl, or is chro moly ok?

I need advice as to which type of sights and optic mount I should use for this rifle. Ideally I would like flip up front and rear sights but which are the best most durable?

I suppose I could get away with a standard front sight and a flip up rear sight. Does a fixed front sight hinder me in any way if I do this? I would think not, but I am unfamiliar with this configuration.

I recently saw a link with a lot of pics of cowitnessed BUIS through Aimpoints. It seems like if the BUIS always remained up it would not hinder the shooter in any way. Is this the case? Are two flip up sights the ideal configuration to go for so I can put them down for an unobscured view through the Aimpoint?

I was considering GG&G, ARMS, KAS, and any other high quality flip up sights. Any suggestions are welcome.

If I don't get the RRA Quad rail handguard I was considering a Knights Armament M-4 RAS for possible future mounting of a weapon mounted light and verticle fore grip. Suggestions welcome for both. I could also mount a sling swivel on the left side of the RAS for a CQB type sling set up.

This weapon would be used anywhere from CQB distances out to 300 meters.

Finally, I would like to get a collapsable stock configuration (ideally a VLTOR or Magpul), but I may have to pay pre ban prices to get the evil adjustable stock and flash hider features because getting the weapon on letterhead is an unlikely option for me. But a slim possibility.

I would like one of those stocks because they seem to offer a better cheek weld to the weapon while shooting. When using an Aimpoint will I be needing a cheek weld or do you shoot more with a heads up position?

I do like the set up on the rifle in this link.
http://mstn.biz/images/Guns/MSTN-M4-GGG-16JPG.jpg

I also like the set up on the green rifle in this link.
http://www.thermaldynamics.com/pictures/mstn/Vltorcolor.JPG

Lots of questions and possibilities. I appreciate any advice offered and thank you in advance for any suggestions.

While the CAR A4 is a nice rifle, I would go with the only model RRA offers with a chrome lined barrel, the "Entry Tactical". With the post ban model, you get a 16" chrome lined barrel that looks like a 14.5" with flash hider due to the mock suppressor.

There is much discussion if you need chrome lining, but IMHO it is definitely easier to clean and gives you more reliability under less than ideal circumstances.

Forget the RRA quad rail- it is too heavy. Yankee Hill, the RRA rails producer, already has a lighter one out and the new SureFire rail shouldn't cost that much more. I would go with the SureFire rail- otherwise you would have to remove your front sight for installation. Or the much more costly route would be to go with a (barrel) free floating RAS II or SIR system.

Also specify that you don't want the Tactical Carry Handle- it is of no use with optics.

Most people consider the Arms#40 back up sight the way to go. While a folding front sight may be nice, it is not necessary.

A Vltor stock is great, but if you want to keep the rifle post ban, a Sully stock or the RRA "Entry" stock with a spacer (both nonfolding but with the right size = shorter than the A2 stock) is not bad too.

Best Regards

Cato

PS: In most of the recent SWAT issues Pat Rogers, a real authority when it comes to the Ar15/M4, has discussed questions which may interest you. I ordered some back issues because of them.

Tactical?

Stock, out of the box M4 or M16A2 clones are as "tactical" as you can get.  Real world tactical, that is, not ninja tactical.  [;)]

-- Chuck

a lot of questions.

get chrome lined.  For a fighting gun it makes extraction easier and a little more sure.

I like the ARMS#40 backup sight.  The aimpoint mount (rail grabber?) is fine if a little bulky.  the knob poking out the side annoys some people but i like the way it works preventing overtorquing and reduced wear on the rail compared to say an ARMS mount.

Front sight won't be a problem and will be one less thing to flip up if you have to go to irons.

I like to keep my BUIS flipped down as i get a more uncluttered view, some prefer to have it up for fast transition.  i say if you don't have time to flip up your rear sight just index off of the aimpoint body cause the bad guy is in your face.

the quad rail is probably fine for your purposes but i believe will require removal of your FSB and barrel to install, also i wonder about the use of VFG on HG that screw on, could they become unscrewed?  No problems reported yet.

I use a cheek weld with my Magpul stock in most positions and thinks its a good idea when you can do it.