I"m no gunsmith, but I would think since it is the same M4 whether it shipped with the 18" barrel and then cut by Benelli/Berreta, that it should not affect the ARGO system. I believe I have read on here or other forums, if you go shorter than 14 then you can start to have some cycling issues and the round type can affect it. I have not tested or seen any of this in action, so this is purely based on other threads I have read. There are plenty of shops that will cut your barrel; Briley, Rose Action, Van Comp, etc. Getting it threaded is where it gets tricky.