It's a more modern upper, but I have no other forum to post.  So I figure I'll take a chance and post it here.  I have an opportunity to trade a new complete generic modern A3/4 upper for a Colt 723 upper that used, but certainly not abused.  The guy wanted $180 shipped for the upper if I want to pay him cash.  But he's in need of a flat-top upper to mount optics, so he's ready for the trade.  I was told it was a Colt C7 upper because of the Brunton bump and A2 EP cover, but 1 of the pictures he sent of the Colt proofs in front of the EP shows a blurry "4" above the gas tube, which led me to conclude it's a 723 upper.  Another picture also shows very shallow feed ramps cuts in the upper.  So now I'm convinced it's a Colt 723 upper.  Should I pull the trigger on this trade?  God knows I don't need another build around this upper

[Edit to add] Upper has tear-drop F/A installed and I paid $100 for the A3/4 upper.

Should I pull the trigger on this trade? God knows I don't need another build around this upper  

Think you answered your own question.  

You would definately have been getting the better of the trade in value 2-3 months ago.  Generic flat top (M4 ramps?) does probably have more value and is definately more desireable today IMO.  I'm left handed and don't own a 723 so for someone with similar tastes and shooting requirements it may be a viable option for using A-1 sights with a hump.  Keep in mind in another 6-9 months the flat top is probably gonna be back to $60 where the 723 will probably hold around $125 again IMO.  Glad I have more than I will ever need.  A-1's,  A-2's,  NM and flat tops.

Think if you really wanted to unload the flat top you could get twice it's initial cost pretty easy right now. edit/  depending on what you paid for it!  

In all the AR's I've owned over the years I've still never owned a M-4.  Have built more than a few but never owned one.  Would be kinda cool to install a SOCOM barrel and do mag dumps if ammo ever gets right again.  Not sure if I'm ready to trust my reloads for FA fire yet.  Probably fine and have way more TLC than surplus just a tad paranoid as it would be near impossible to replace any of mine right now for twice their original build costs.

Personally think you could get a better trade than a 723 upper for a new flat top receiver right now if you advertised you wanted to trade.  Lot of tacticools out there with retro but no flat top receivers.  That $180 723 may eventually sell but they aren't retro and actually aren't nearly as versatile as a current production M-4 which I'm sure you already knew.  Still a bastard child in the AR evolution.  Sometimes condition is key.  Lot of Bubba'd stuff out there right now too.

[Edit to add] Upper has tear-drop F/A installed and I paid $100 for the A3/4 upper.

DPMS tear drop is $10.  Colt is $20 plus.  $100 for upper was probably a little high but I've paid it before.  I prefer to buy bulk in the $50-60 range but add a $8 door assembly and a $9 assist and the price climbs.  Not to mention sights.  I'm really not seeing any real value in either piece down the road.  All in what you want.  In our conversations you wanted a flat top or I thought you did.  I still think you could do better than a 723 for it right now but it's Colt and there aren't a ton of them around either.  Almost sounds like you just want to do a deal or you can help the guy out and be a samaritan.  Kind of a win! win!.  Decisions,  decisions!