I have a practically new Colt 20" A2 upper that I never use.  So I was thinking of converting it over to an SPR Mod 0 with plans to 1)Test barrel accuracy and 2) Upgrade to an 18" match SPR bbl or 6.8mm later.  But the barrel will be the base for now.

So, who's flattop A3 upper would you recommend?  I figure that my criteria will be (in order)
1)Quality
2)M4 feed ramps
with a distant,
3)color (pref. Colt Light Grey Sporter)
4)Price

Color is really not critical as most components come in combo colors anyway (see PRI's flip up sight).  And I don't mind paying for quality.

Thanks!

You're going to need a Colt's M4 or M16A4 upper receiver to get M16 grey color.  These will both have the feed ramps.  Note that's a M16A4 upper, not A3.  The M16A3 upper is the same part number as the M16A2.  

-- Chuck

Chuck,  I never considered the M16A4 upper and was not aware that it was designated so.  Thanks.

I already have an all Colt 16" M4 upper and that upper is very black as compared to my Colt sporter lower.  Again, not that color is a huge factor.

Color aside.  Do you only recommend Colt as a quality upper?

The M16A4 (flattop) and M4 (all but the first few are flattop) uppers have different part numbers.  Look in your M16A4 upper and see if it has the feed ramps.  

It's been reported to me than they do, but a closer review of the specs indicates they probably don't (despite my note above) as there's no difference between M16A2/A3/A4 barrels and ramps in the upper receiver would create a lip which might deflect the bullet tip.

-- Chuck

Chuck,

Yes, my M4 upper does have feed ramp cuts.

You can match the barrel ramps to the receiver ramps with a little effort.  My wife's son at Fort Knox has a personal M4 carbine I built up for him with a ramped M4 upper and Bushmaster M4 barrel.  Wasn't 10 minutes work to match the barrel ramps to those of the receiver and eliminate the microscopic lip.  No reason a 20" bbl can't be fitted.

-- Chuck