Quick question about relative scale

So I have a vector drawing on my stage…and it’s 1000px wide.
Say I resize that with vector_mc._width = 500px (which is visually the same as changing the x scale to 50).
Is there a way to set the new width (500) as the absolute width…meaning if you asked the vector to scale to 100 it would go to 500px and not the original 1000px?
It’s a basic question but it’s something I never learned without any formal teaching.