Wow! I'm delighted to see how this thread has taken off!
OK, lets crowd source this right now.
I'll dig out my notes and post again soon.
For now, I am thinking I do NOT want to simply duplicate to M&M gun.
I want to create something new, of our own.
My temporary working name was (last name) Modular Sporting Rifle, RMSR.
But I am fine with a name change.
I intend for it to be several calibers, and an easy barrel change, hence the Modular title.