Buying a used AR15 upper part 1 — A look at a Colt 733 upper


You can get some good deals buying used parts online.  I buy a good deal of stuff used on the Equipment Exchange on  The problem is that when you buy used you are taking a large risk, and you really need to know what you are purchasing.

Not only are there scammers out there, there are also ignorant sellers who may be selling fakes thinking that they are real.

Recently I purchased a used Colt 733 upper.  The C stamp on the upper and the C MP CB on the barrel lets me know that they are Colt parts.

2013-11-06 13.43.40I paid $500 for a complete upper including bolt carrier group.  To me, this is an excellent deal as Colt bolt carrier groups often run 2-300 dollars on their own, and often similar uppers with out a BCG will run $4-500.

When I got it, the first thing I did was inspect for wear, internal and external.

Colt 733 Upper

Colt 733 Upper


The upper and barrel exterior both showed wear from use.  This was a police trade in, and the wear on it showed that.  Wear on the barrel from a rifle rack, wear on the front sight base from some sort of sling or accessory attached there.  Wear on the carry handle from a scope mount.

Colt 733 Upper


The two spots of bare aluminum on the inside of the carry handle look like the wear marks left from a Trijicon Reflex sight in a carry handle mount.

Next I looked at the bolt carrier group.  First I checked to be sure that the parts I got were Colt.

Colt 733 upperColt 733 upperColt 733 upper


The markings all checked out.  A C stamped on the bolt carrier, A MPC on the bolt, and a C on the extractor.  The two main wear points on the bolt carrier group that I inspect are the bolt face and the cam pin.

Colt 733 upperColt 733 upperThe bolt carrier group was clean, and while the finish has been worn off the bolt face, bolt lugs, and the cam pin neither show excessive wear or pitting.  So this bolt carrier group has been used, but not excessively so.  More heavily used uppers will have grooves in the cam pin, and pitting on the bolt face.

The most interesting thing about this 733 upper is that it has M4 feedramps.

Colt 733 upper


I was under the impression that the 733 upper was out of production before the M4 feedramp change was made.  Turns out I am wrong, there are C stamped Colt C7 type uppers out there with M4 feedramps.

The only problem I had with this upper is that the little C-clip that is the ejection port door retaining ring was missing.  Fortunately I have many of those laying around, and I replaced it easily.  The seller of this upper even threw in extra items with it, making the deal even sweeter.

Colt 733 upper

I got a good deal on this upper and I am very happy with it.  In part two of “Buying a used AR15 upper” I will tell you of a couple of cases that did not work out so well.





  1. That’s interesting. I have bought many things from private sellers online and have never been cheated…..but…
    On the same equipment exchange, I bought a brand new LMT complete upper w/some small extras for about $700, which was a pretty good deal. I paypal’d the seller, and was told the upper would go out that day, and he’d send it out that evening with a follow up email providing a tracking number.
    Received nothing that evening but didn’t sweat it, he would be pushing it as far as time went.
    However several days went by, still nothing. Emailed him and was assured all was well, but then another week would go by.
    Long story short, and several more email contacts, which always just got me another slew of excuses, that sinking feeling that I had been getting worse, changed into what I was ready to admit I just got screwed out of 700 bucks. Not a good feeling. During the final few days I was contacting my lawyer, paypal, and my credit card company, when lo and behold the thing shows up at the door.

    Why he took so long and why the seemingly disingenuous excuses, I’ll never know, but I knew how I felt about losing that much money.

    Much of the items I’ve bought, especially used, were better than I expected. I just bough a ‘new” use Aimpoint ML2 sight for a new build, and the seller indicated it had been used and not babied, but when I opened the box, and checked it out it wasn’t what I expected, for the most part it looked almost new and could almost pass for new. Operated like new as well.

    Glad your upper had a happy ending. So far, except for the weird deal with my upper, I’ve been lucky in that respect…



Please enter your comment!
Please enter your name here