I have a AR-15 complete upper in 7.62x39, just got it in and shoots good, but in slugging the bbl to get an exact measurement for loading, I found that, starting the ball from the chamber end, It was hard for about 2 or 3 inches, them it practically fell thru the rest of the bbl. The measurement was .306. That is too small for a 7.62x39 or course. I have heard that some barrels have a tight spot up where the barrel screws to the upper. This is the area that it is tight. What should I do? Wallacem inGa
