I came across an AR yesterday that I was considering buying. But I could not determine who the upper was made by so I hesitated. The lower is made by Bushmaster, but the upper has absolutely no markings on it whatsoever other than an "R1" or perhaps it's "RI" within a circle of the front sight base. That's all I have to go by and it seems almost every AR has that same marking or a similar one in the same place, so that's not much help either. The finish appears to be ever so slightly darker than that of the lower, and appears it might even be slightly thicker too, if that makes any sense. The upper is also a flat-top. I have a Bushmaster 16" HBAR and it's looks similar, but the Bushmaster upper is clearly marked on the barrel that it is a 1/9 twist and 5.56mm. This one I am describing has nothing other than that R1 marked on it. So how can I determine who made it?

Every AR I own must be capable of using full power 5.56mm ammo. Commercial spec chambers are ok with some, but I just don't want any of them. That way I can shoot my load of choice (Federal or Winchester M193 spec) without having extraction and other pressure related problems. Is there an easy way to determine at least what chamber it has? I can live with the upper being a kit or made by any of the various manufacturers (so long as it isn't a Hesse or something...lol). But having the 5.56mm chamber is a requirement. Can anyone offer any help? Oh yeah, the carbine is priced at $600 and is in overall good condition.

-Charging Handle

Good luck. If there are no markings on the barrel...it may be that the upper is just odds-and-ends put together. I've never seen the "R1" markings (someone out there knows what it is though), but it's doubtful that the upper is Bushmaster. Unless the dealer could give me some history or point me to someone that could, I'd walk away...unless you're dead set on taking a chance on getting a "good deal". Good luck.

It's not in a shop, it's just a gun a fella I know traded for. That's why I have no idea about the history. We shot about 40 rounds of early 1990's UMC through it and it never bobbled. It is my understanding that UMC loaded their ammo pretty hot back in those days but I have no idea if it was in the M193 range. It was also pretty accurate as well considering the low quality scope and the extremely low rings the previous owner had on it. Good grief, you had to turn your head sideways and lay it all the way down on the stock to see through the scope! I like the gun, I just wish I knew who made the upper and whether or not it had a  chamber compatible with mil-spec loads. I'd buy it in a heartbeat if I knew it was what I wanted.

-Charging Handle

Thanks Troy. I was afraid of that. I did go back to look at the carbine again, but in the end I just decided against buying it. I field stripped it to see if I might run across some markings on the bolt carrier assembly or inside the upper receiver itself, but I could find nothing distinguishing at all. On top of that, this closer inspection also revealed another problem. The only way to remove the rear takedown pin was with a damn brass mallet and a drift punch! I never saw a pin so tight. One thing is for sure, the fit between upper and lower was definately tight enough on this carbine to not require any of those aftermarket gadgets! LOL. But I assume something was pretty out of spec to cause this, so I chose to pass on it. I didn't really need it, but thought that at $600 it might make a good new addition. However, I have rifles I trust and don't want to take a chance on getting a piece of junk.

While being able to build your own AR rifles from kits has certainly made it cheaper to own an AR, it has at the same time destroyed the used rifle market. There are so many of these floating around anymore that unless it is specifically marked, you have no clue what you are getting. It should be a requirement that the manufacturer and twist rate/chamber be stamped on the upper somewhere. Otherwise someone could buy a kit, build a lower with whatever marking they choose and later sell it as a Colt, Bushmaster, etc for a price far in excess of it's worth. I am amazed at how this practice can be allowed. I am sure many people who were caught unaware have been ripped off in this manner.

-Charging Handle

I have a 20" HBAR 1x9 upper from M&A Parts. It was in the kit that I purchased from them and it has the following markings on the front sight base:D99FN1. The FN is circled and that is what I think you saw. It's very hard to decipher unless you look at it real closely. At first I thought it was an R1 too until I looked at it again. There are no other markings on the barrel. It fits great onto my Olympic lower.