I am putting together two Buly kits from K-Var.  I just want to double check my parts count.

OOW stamped receiver = 1 part
RSA trigger group = 3 parts
USA made pistol grip = 1 part
USA made butt stock = 1 part.

                  = 6 parts.  

Due to the muzzle break, do I need to add a new gas piston as well?  Where would I pick one of these up if so.

The list you show gives you a total of 6 U.S. parts as required to use the muzzle break. Just remember to have the break permently attached and remove the tabs on the bayonet lugs. You should be good to go. Some things you will find out on the assembly as you go, get a good game plan from this site and links to others. If you are not sure on somethig ask this site is a great resource, it has been a god send for me.
Best of luck on the kits.

Thanks. I thought it was 6 for this set up, but wanted to be sure.