I just bought a used Concept XR and I love this thing. I believe there are 3 (4) variations of this puppy just in the last couple years. Here is what I found from my research.
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1. The original is the Concept Lite with the bolt action. Let's call this rail the "integrated" picatinny rail like in the second pic from the OP in the thread.
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2. The next is the Concept Lite XR with the same integrated picatinny rail and the new side-lever, floating hammer and other "XR" enhancements. It still uses the same old magazine. This is the one I have. The "old" magazine issue doesn't bother me because aftermarket Carm magazines are fantastic. It cures the issue some have with accuracy.
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3. The next one is the same Concept XR but with the newer magazine. I'm not sure what else has changed. This is the 2nd picture in the original post.
I know AoA has made colorful versions of this. I wanted an orange or OD green version, but I don't believe they ever received a .22 version of the OD green - at least I couldn't buy when I looked. Here is a pic they sent me to tease me.
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They told me it would be 3 months before another shipment, which is when I bought a slightly used #2 version. I was already waiting several months and they can't seem to get them in stock.
4. The newest version that AoA will receive (in 3 months!) is the model based on the Atomic/Ranger. We'll call this the "picatinny rail sticks out" version. That is like the first pic in this thread. The side rails have been removed to reduce weight, although it looks more awkward to hold IMO.
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Honestly I love the old style frame better anyway. While I would love a green or orange or even purple version of the Concept XR, I'd rather have THIS frame instead. The magazine is a moot issue for me with the Carm option.
Edit: So last I heard, they ARE getting a shipment of those OD green Concept XR's in, but it will NOT be like the picture I posted above. It will be the Atomic/Ranger frame. In other words, I have
no idea if anyone was able to buy an OD green Concept XR in .22, that I posted above. It might be a unicorn.