I recently bought a RRA lower and A2 upper to build a rifle. After I assembled it and put the barrel on, I tried fitting the upper to the lower. I can put the front pin in but the back one will not go in. The upper will not line up with the lower. If I push down really hard on the upper I can make it fit, but then once the pin is out, you have to hit it hard to get the upper off the lower again.
I did take my other RRA rifle apart to see what the problem was too. Using the new lower with my old upper, everything went together just fine. But if I put the new upper on the old lower, the back pin wont go in either. So that means its something with the new A2 upper I bought. And it does seem to be rubbing on the back by the stock.
Does anyone have any ideas? Or is this a problem with this upper? I bought it new from a advertiser on this site.