Question?  I have 2 ar's, a bushmaster and a S&W.  What is involved in changing them to 6.8 rem spc.  Just new uppers and mags, or is there more?  Thanks.

The only difference, overall, is bolt, barrel and magazine.

If you have a complete 6.8 upper assembly and bolt carrier group, then you just pull the pins, swap the uppers, load the new mags and go shooting.

If you just have the barrel and volt for the 6.8 the swap is a lot more involved, but not really too hard.  Some special tools are required.  Check the "Build It Yourself" section for how to swap a barrel.  It's simple.

The difference is the bolt, barrel, muzzle device, and magazine. Get yourself a complete 6.8 upper and some 6.8 mags and you're set.

Yup - get one.