If the spokes are 'not that tight' and they are stripping you are using 2.0 nipples on 1.8 spokes.
Simple mistake everyone has done it.
Just buy new nipples in the correct size.
It is not a deadly sin to build with used nipples but as so many have stated it wastes a lot of your time and is not recommended.
I would also recommend only using brass as aluminum is not as strong.
Enjoy