semantics but somewhat important, gatling implies that you can cancel certain normals' animations into another one; link means that the animation finishes completely but the hitstun is long enough that another move can still combo. provided that you're close enough after the 6k, any move with a short enough startup can combo. according to the framedata 6k has 11 frames recovery, and as a level 4 attack would net 17 frames of hitstun on standing and 18 frames on crouching. assuming your timing is perfect, that means that 2p(4f), 5p, 5k, and 2k (5f) startups can link, and against crouching you might also get 5c.s and 2d with 7f to connect (not 100% sure... kinda forgot). a ch gets +8f stun, anything short of 6k/6h/d works in that case.
the usefulness of 6k links is kinda iffy in the first place, the old 6k>5s> chain was the reason to learn it, and with the +2f recovery 6k gained in ac, on paper it seems to only work vs crouching with 0f-margin of error execution. i'm guessing that you mainly get 6k to connect as a frametrap in a blockstring, but odds are that it's rarely deep enough for anything big. 6k>2k>x for knockdown is probably as good as it gets, a cancelled special could work too.
6k is probably used most often after a blocked 6h, it can also safely follow up 5h unless ibed. it normally has +4 frame advantage on block, so you have time to do any of the stuff missedfrc posted and more. i might add that 6k>5c.s> still works fairly well as a blockstring until you get pushed out of range, and 6h>6k>6p> usually forces fd, both also upping guard quite a bit unless shielded.
then again, i haven't touch ac since bb came out, so i could be remembering completely wrong...
