You see the Difference?

[Steve_evetS]

I have seen this in an over gassed rifle and external piston..

It looks like it is unlocking prematurely from what I can tell from the pictures..Is there a gouge in the upper receiver cam lock pocket?

Look on the front of your barrel extension lugs and see if there are any marks or gouges too..The barrel extension could also be clocked..

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The Lug Wear in the first 2 pics the other three shows the URR going in and engaging the insert through the upper reciever. Which aligns perfectly. I am using the Midwest URR which has the sail.