Is it the very end of the barrel that is moving or is it the whole barrel and receiver? Try shaking it...-Y
thanks guys for the replay,i was pretty sure their no movement is aloud by the reciver ,what I did I took the pin out,the one which holds and locks all togheter,it has a spring under, a pin or a toth,anyways I greas it put back togheter,was fine for I while,meanning 25,30 shoots and it got luse again,but I I know this that the bol tor scrue which holds everything in place it gets luse all the time not much ,but enough to make the barrel go up and down,i used blue luctite this time to see if it holds,