Just in case the original poster, who is using a Canon, isn't aware of and confused by Nikon's designations:

"AFC" is "continuous autofocus".... which is the same as Canon AI-Servo.

"9-point" is a "zone focus pattern", using only a select group of AF points out of the D7200's 51-point AF array. The Canon T3 only has has 9-points total and it doesn't have a zone pattern. Earlier recommendation to use only the center AF point of the T3 is the best suggestion for that particular camera (that's the only higher performance "cross type" AF point in T3... its other 8 are lower performance, "single axis" AF points).

"2500" = 1/2500 (original poster was using even faster 1/4000... the fastest shutter speed available on T3, so "camera shake blur" is highly unlikely).

"Aperture 6.3" is "wide open" on a Tamron 150-600 at 500mm. f/6.3 also happens to be the same aperture the original poster was using with their 28-300mm zoom (at 300mm). Don't know it that's "wide open" with that lens or not.... but it's probably very close to it. Many 28-300mm are f/5.6 at 300mm, at best (incl. Canon's). f/6.3 is only 1/3 stop smaller than wide open anyway. Some 28-300mm are f/6.3 at 300mm (Tamron's for example). Using a telephoto lens wide open or very nearly so makes for the lens' shallowest possible depth of field, and that in turn makes focus accuracy most critical. Unless you are looking for maximum background blur, try closing down the lens aperture a stop or so, to have a little more "forgiveness" of minor focus errors. (Most lenses also aren't at their sharpest wide open.)

Nikon "AFS" is same as Canon One Shot... both are normally used for stationary subjects.

"BIF" = "birds in flight"... a rapidly and often erratically moving subject that's difficult to track with a single AF point (hence using a 9-point zone focus pattern instead... but in T3 you'd have to use "all points/auto").