If the gun is assembled correctly and it is pretty hard to assemble one of these incorrectly even if one tried. It is one of 2 things ....the bore or the scope...semi-autos you have to be careful with crown when you clean them a few nicks and the accuracy goes out the window. The other variable is the scope and I think that might be your problem . Put another scope on the gun that you know works well and try that. I had the same thing happen a few years back I had a custom Model 70 300 win mag that would shoot tiny little groups. I took it home from the range and gave it a good cleaning on the Outers Foul out III since it had a bit of copper in the bore. Back at the range and it shot terribly. I thought it was the cleaning job I did but in the end it was a Blurris scope that went @@@ up. I just put another scope on it and it was back to normal. I haven't touched a Blurris since