[mike]

Stop whining around, man. 

 

You wanted a cheapo lens, you got one. +5 AFMA on the D500 - are you joking to complain about that peanut? I had lenses which needed around +15, one was +25. So what? Do it and get sharp pics afterwards. Why are you trying so desperately to ignore the fact there are tolerances - and there are as well, at least in your D500, inbuilt routines to compensate them?

 

You can try to send the lens to Sigma to adjust it. Matter of fact, I don't know which Nikon serves as reference to their own calibration, but it can't be a good one - I always have to adjust the lens, no matter if Nikon or Sigma (or Tamron). The 100-400 was a pure exception in my eyes.

 

I've had a Sigma 105/2.8 macro for too many years. AF isn't fast, but never had any focus issues with it.

 

When Canon 'upgraded' their firmware and the sigma didn't work right I sent it to Sigma for an update. They're customer service was great. The update was free and it only took about 10 days from the day I shipped it to the day I got it back. The paper that came back said they checked the optics too. It may be worth sending it in.