I have been thinking about this for a while and am completely convinced it will work. I want to form 1 my ACR but I can't find any barrel assemblies that are shorter than 16". Then I was looking at some barrels online and a standard AR barrel seems to be begging to be turned into an ACR barrel. It has the centering pin correct gas block diameter and gas port alignment if you move the adapting pieces and the piston system over and cut the piston to fit the shorter length I feel like it would have no problem running with the shorter barrel. Please let me know what you think this is something I've been pondering for a while.