You can use pretty much what you want as a primer
This is AK stainless steel onto stylnrez matt grey primer.
You do not have to use black gloss base on every metal. It is always wise to get some plastic spoons and practice on them with various base colours as you can actually change the perception of the metal with the base and you are not limited to a gloss one. Try a matt white or gloss white and see what the difference is between the same metal colour on those backgrounds.
Also get some of this:
I love both AK xtreme metal and Vallejo Metal colour. they are my metals of choice and I do combine them on my aircraft engines for different colours on parts such as AK stainless steel for the cylinders of the rotary block (it has a slight bluish tinge) and on a matt grey primer looks the job and Vallejo Magnesium on the exhausts.
Both these dislike being masked and I usually put the Gauzy agent on to silver metals and a matt or semi gloss onto red or black metals as a protective coat. Once cured ( give it all a day) then masking will be no problems.
Once I have finished the Waffentrager in the Armour section then I will be doing ZM's Shinden in 1/32 you might want to follow that and see how I do the metalwork for the engine and airframe