A question, very curious all new fighters* get a gun and no the two Chinese J-20/31 mainly the J-20 seven build from 4 years ! so guys ?
* except F-35B/C in a external pod for specific reasons
Your grammar makes no sense, but I assume you're asking why J-20 and FC-31 do not have guns whereas all new fighters (outside of F-35B/C) do.
It has been discussed before, to great length. We have identified what may be J-20's gunport many pages back. FC-31's gunport has not yet been identified.
The reason we have not been able to fully confirm J-20's suspected gunport or identify a possible gunport on FC-31, is because they are stealthy aircraft, whose gunports are typically well hidden and may be smooth against its fuselage (like F-22's). Some stealth fighters like F-35 or PAK FA have more obvious gunports, but that doesn't mean J-20 or FC-31 will have such obvious ones.
The chinese military is also very opaque, meaning we do not get the open diagrams and cutaways of J-20 and FC-31 that we'd get with other nation's fighter aircraft, where one can easily ID a gunport through official photos.
The fact that we typically do not get high quality pictures of J-20 and FC-31, and the fact that their paint schemes make it difficult to identify precise small panels that may indicate a gun port also make it difficult for us.
The only way for us to truly eventually positively identify a gunport on J-20 and/or FC-31 is either through wallclimber photos of them happening to open a gunport door on the ground (unlikely), or more likely we will probably have to wait until we get officially released footage or pictures of J-20 and/or FC-31 testing their guns... which is likely going to take years to be considered declassified released.
In other words -- the fact that we can't see an obvious gunport does not mean they are not there.
So the question you should be asking is not "why doesn't J-20 and FC-31 not have a gunport," the question should be "why have we not identified J-20 and FC-31's gunports yet?"
