I plan on buying a 14.5" barrel, pinning a phantom flash hider (or should I use a vortex?).

But for the m4 handguard, a KAC RAS is the correct part, right?

If so, is http://www.ebay.com/itm/Knights-Armarment-Company-RAS-Quad-Rail-/201091520466?pt=LH_DefaultDomain_0&hash=item2ed1fd17d2 legit?  There are several vendors selling what look to be surplus for around 90 to 100 dollars.  That seems awful cheap.  Any suggestions?

Put a WTB ad up in the EE or keep searching the EE misc. accessories or used upper parts. The RAS usually goes for 100 or with a few covers and maybe the VFG. If you find a P & S RAS that is legit too, KAC and P&S are the .mil suppliers. They are on here all the time.  As for the flash hider perhaps the BCM A2X is another choice.

Thanks for the info.  So do you think that eBay one is not legit?

Looks like all the Knight's RAS I've ever seen, the fakes can be id'd by the numbering on the rails, it is bright white instead of a grey like KAC uses. The ebay one also comes NIB with all accoutrements, looks like a fantastic deal. As far as correct part that depends on what you're going for, the stnd. M4 uses the RAS, the SOPMOD uses the RIS.

William

^^ Not to nitpick, but your example has the wrong buttstock.  

OP, the correct flashhider would be the standard A2 birdcage, if you are looking to duplicate the M4.  Somewhere on here I saw a picture of an extension that looked pretty good with the standard flash hider to make the barrel the requisite length.  

As for the rail, the M4 comes standard with just plastic handguards, but most combat arms units have Knights Armament rails on them, the one you linked looks to be correct.  I wouldn't sweat the brand personally, unless you want maximum authenticity.  If that is the case, a 2012 to 13 model LE6920 SOCOM is exactly what I carried in the 82nd, except for the barrel length and not having Burst on the selector (which we virtually NEVER used anyway).  

If you wanted to build it "right" you would also need either a Trijicon ACOG TA-31 or the M68 version of the Aimpoint Comp M2, a "KAC Broomstick" forward grip, a Surefire weaponlight at a minimum.  We also had IR lasers, but I don't know how a person could justify that without also buying a rather expensive set of NVG's that would be required to even see the laser.  

If I ever had a couple thousand bucks laying around I didn't need, I'd rebuild my old M4 that way.  In the meantime, my PSA blem feels no different in hand than my old M4 did.  

Edit.. nevermind.  

The M4 Modular Weapon System comes with the RAS

Yeah, I remember hearing that name a time or two.  We never called it that.. they were just M-4's.  To me, for them to look correct you'd need to throw it down on a dirt road about fifty times, then it would be getting close.  And lose all the rail covers, almost nobody had those, except the POG's back at the FOB.  Those never went anywhere but the chow hall, the MWR, and the PX.  

The ras in rifle or carbine length is expensive brand new from kac. However due to the large numbers out there, and probably many 'procured' from unkle sam, they are pretty cheap on the second hand market. That said there are fakes. Ebay is loaded with fakes from china. So if you cant tell, do not buy there. I think the EE is a safer bet. I got my rifle ras for $85 and its legit and super nice. Kac sells the blems for $150 if you want to buy from the manufacturer. Either way, youre probably safe.

His stock is correct for an M4 produced from 1994 to 2003.

I just got a KAC RAS on ebay for 110 shipped. It appears to be brand new and never previously installed.

I got to looking around, and yeah I stand corrected, it is a correct stock, looks like the old CAR stock was that way too.  My bad.  I just never had one like it.    Back on topic :)  

Bravo Company has a good sale on both BCM and LMT M4 uppers, slap a factory-seconds M4 RAS, a Matech BUIS, your choice of optic and your lower and boom. You're done.

BCM M4 Upper - $439

LMT M4 Upper (with double heatshield handguards) - $538.35

KAC M4 RAS Seconds

For the record, the M4 I carried in Iraq in 2003 had that exact CAR stock.

KAC RAS bought on E-bay $135 NIB complete kit
Colt 6921 with pinned KAC NT4 FH- OAL 16.25 crush washer & couple shims