Buffer change with new upper?

[kac]

I have an LWRC M6A2, 5.56, 16" barrel, which is approximately 2-3 years old. I am buying a Noveske 6.8, 16" upper this week.


Should I consider changing the buffer and spring because of my shooting this new caliber? Should I change back when I swap uppers?

Thanks for any help you guys can suggest.