Don't understand the "still" part of the question.
D D, it makes perfect sense to those who used one.
Jerry
Oh. Well, try as I might life ain't long enough to like them all I guess. Won't bother y'all with the list of the ones I still like, it's kinda long. I have fond memories of the 20mm.
I thought that I would throw a 30mm into the mix. I never worked on a 30mm, but I've spent a lot of hrs with the M61A1 and M39 20 mm guns. Here are the M61 and a GAU 8 guns firing. Nice groups. Those A10s are so quiet. By the time you hear them, you're dead.