Simple question can it be done? I'm thinking I would just need to swap the follower, and spring. I'm interested in geting a 6.8 upper and do not want to buy new mags. Does anybody make a conversion kit?

Can just a few rounds of 6.8 be fired from a stock 5.56 magazine in an emergency or for quick test firing purposes?
Off the AR topic, but I'm considering buying/trading to get one of the new Ruger Mini's in 6.8. As far as I know, the only mags available for them are the factory 5 rounders. I was wondering if a regular higher capacity Mini-14 mags could be used for a few rounds in a pinch.

I shoot 5.56mm and 6.8mm. In a pinch I have been able to shoot clean five round runs of 6.8mm out off my 5.56mm mags.  Any more than 5 rounds and the mag won't fit in the magwell due to spreading of the mag walls.

TG

Larry @ C Products answered your other question.  "NO!"