Impossible? Lol? You don't need 10 SSR wpn grids to be using SRs as fodder. If you already have wpn grids that are full SR/SSR, there's no real point replacing one SR assault with another, is there? You'll most likely just be wasting a lot of resources if you do so for minor stat upgrades, especially since the eventual goal will be to replace all SRs with SSRs anyway. ¯\_(ツ)_/¯