Previous game patch inside NS2 ?

Hi , when i messing around with game folder Natural Selection2/builds , i can see many .zip files with name like this " build_227 ....to build_251"

So i wonder if i extract these file into main game folder , would my game become "downgrade patch" ? I just want to play old builds to try things out

For example if i extract .zip files "build_249" into NS2 game folder and launch steam ,will NS2 become from 251 into 249 patch version ?

Thank you and hope gane dev answer my naughty question