To be honest i tried the primers and did not like them at all, the paint range seems fine to me no issues like other people have reported.
I switched completely to Mr Hobby's Mr Finisher 1500 thinned with Mr Levelling thinner, which I mix around 50/50 with a 0.3 or 0.5 airbrush. I always sand the bodies with 1000 grit sandpaper first, followed by a wash with dish soap and leaving overnight to dry. Then, I give them a quick once-over with some thinners to remove any grease or fingerprints.
Spray booth wetted with some paper towel on the bottom also damped to catch any dust even a little water misted over the surrounding areas including myself, I normally lay 3-4 layers of undercoat (base coat?) and leave for 24 hours to cure, Mr Surfacer is super smooth and barely needs any sanding if i do i use very fine grade sanding sheets somewhere between 2000-3000 grit.
TBH on a break from building at the moment due to personal issues, when i return and get back to my youtube channel i will be trying some other primers from the likes of Ultimate modelling products, Pro Acryl. Ammo one shot etc etc.