We sent our friend Paul Glasco at Legally Armed America one of the first RMCS-4 Multi-Caliber Rifle Kits, and he put together a terrific video showing how all the components of this 4 caliber AR system work and interchange.
Check it out on YouTube at: https://youtu.be/XLGDEuEIchM
If you ever have questions about your rifle, you are always welcome to call Windham Weaponry Customer Service (Toll Free: 1-855-808-1888). Shoot Safely!