I am amused by all this speculation about j-20’s gun and how I-20 must have a gun.
I think it is clear j-20 doesn’t have a gun, and I think it was a bold, but correct decision on the part of the PLAAF to dispense with the gun. The gun is an anachronism whose real value was exaggerated all out of proportion by a very particular set of circumstances the US encountered over Vietnam and the Israelis encountered in 1967, both half a century ago.
A high end super-cruising stealth fighter has no business attempting to get into any gun fight with either opposing high or low end fighter. It won’t be strafing ground targets either. Putting a gun on them betray an bad tendency to want to make a fancy fighter all things to all people, and betray a lack of clarity in operating doctrine.