Recently purchased this lens for my a6300 (KEH 130). It is an unusual A mount because it is a telephoto with optic stabilization--recent Sigma lenses for A mount don't have it. The lens is noisier than the HSM lenses but appears to focus quickly and accurately--probably not as fast as the Sony FE 70-300 which costs $1000 more.
Went down to our harbor (Bellingham) and took some BIF pictures) With a sky background the lens had no difficulty. Against a busier background it had some problems finding the bird.
Off to Alaska next week will test the lens further.
Here are a couple of my successful images.
https://www.flickr.com/photos/147204045@N03/shares/470Sz4